Completing the Great Lighthouse right after the AD crossover did wonders for my finances, especially as my Expansive civ of coastal cities began popping out harbors left and right. If you look at the picture on the last page, my science rate was producing 46 beakers/turn. (This is possibly my favorite new feature in Beyond the Sword; the ability to compare science output instantly with just a screenshot will make reporting day much more interesting!) That number instantly leaped up to 61 beakers/turn when the Lighthouse finished, plus the additional gold allowed me to tick up the science rate another notch, for an even higher total output. Seven turns later in 115AD, I was researching at a sustainable 99 beakers/turn - more than double the previous rate! The expansion makes it easier to SEE the change in beakers, without having to root around in the F2 Financial screen.
How do I know this? I have a screenshot from 115AD, which I snapped while exploring with my scout. Suryavaram was starting to build up a decent-sized army, and I had to keep an eye on it:
Nothing TOO dangerous there, although my military mostly consisted of an archer and a pair of axes in my border city of Guimaraes. One nice thing about having Open Borders is that you can snoop on what the other guys are doing; no need for espionage points if you do things the old-fashioned way!
In terms of research, I continued down the bottom of the tree by going after Machinery, then paused to grab Aesthetics/Literature (for Great Library purposes) before returning to the "Guilds" line for Optics. Got to get those caravel unique units as soon as possible - we want colonies! As usual, I used trades to fill in the techs I missed:
Currency was especially noteworthy since my economy was heavily dependent on trade routes. And now that courthouses provide Espionage Points, they seem more necessary than ever. EVERY city pretty much needs a courthouse now, as they're the only thing that provide EPs for the entire first half of the game. Organized correspondingly seems like a more useful trait now too. Anyway, the extra gold from these trades allowed me to research at a deficit and push further ahead on the tech tree.
Here was another event that seemed interesting:
I can see Sirian's handwriting all over events like this one. Nothing too groundbreakingly powerful or crippling, posing an interesting choice - and spiking the wheels of "formula" players who can't adapt to changing circumstances! Always a good idea to keep some gold on hand now to cover the costs of events like this one; I was able to avoid having to rebuild the forge in Lisbon because I had just enough to foot the bill. It reminds me of the events in Master of Orion; fortunately there doesn't seem to be anything quite as bad as the Assassination or Space Monster events in this game!
By the way, I noticed when exploring Mayan territory that there is now apparently a CITY also named Chichen Itza! Was that really necessary? I mean, it seems like that's only going to cause confusion... 
These were peaceful years for my civ, passing relatively quickly as every city continued to build infrastructure. I easily reached Literature tech first and built the Great Library:
On the same turn, I discovered Optics and started putting my first carracks in the water. Now we didn't put any naval unique units in the release version of Civ4 because there was pretty universal opinion that the naval unique units in Civ3 were either awful (English Man O' War) or incredibly overpowered on certain maps (Byzantine Dromon) without much middle ground. The carrack is basically useless on pangaea maps, but its ability to carry normal units (not just spies and Great People) makes it rather formidable on continental and archipelago maps. On a Terra map, you could colonize the New World centuries before anyone else could even get there! Since I had already decided to play this game peacefully, setting up overseas colonies ASAP seemed like the best way to proceed.
Even as my first carracks hit the water, Murphy struck again:
Why yes, that IS the free Great Artist that the Dutch are stealing from me. Argh! 
I did found Taoism in 790AD, which was irrelevant because I never bothered to spread it around and had no desire to convert (for diplomatic reasons). Considering how fast the AIs were at building those wonders early on, they certainly were slow at researching Philosophy... I also obviously picked up the circumnavigation bonus, in 805AD, as I scouted out the exact loctions of the offshore islands. (I knew they were out there in general, but not the specific spots.)
Meanwhile, Justinian had built the Apostolic Palace wonder, and no sooner had he spread the Buddhist faith to the other civs than he was calling for the diplo victory:
This was the first I realized that only those cities with the Apostolic faith present in them (Buddhism, for this game) got to vote in the elections. For example, even though I was actually #2 in world population, I had essentially no representation worth mentioning. Since it's actually possible to win the game this way, there are all sorts of potential exploits that this wonder opens up. You can have 90% of the world's following of a particular minor faith, like Islam or Taoism, and then vote yourself the game's winner just by converting ONE city of each other civ to the Apostolic faith. Uh... needless to say, that seems... off. 
I'm hoping that Firaxis changes the formula around a bit in future patches, because this is just bad. They certainly could have used some of my input on this one! I think I did more work in testing the UN victory than anyone else before release.
Anyway, my Colossus/Great Lighthouse combo turned out a Great Merchant for my second Great Person, which I cashed in for a trade mission worth 1950g in 930AD. Literally on the next turn, I landed my first colony overseas:
With two fish for whipping as well as copper and gold (a resource I lacked at home), Braga seemed like a great base for the colonization of North Island. I even popped a goody hut in the island's interior and got a warrior out of it! Heh. Once the blackness on the inside was mapped out, I could draw up a dotmap for the island:
I would end up founding all six cities exactly in the spots indicated, neatly doubling my mainland territory to a full dozen cities. Purple dot is the strongest location, and the future Forbidden Palace site. It will also be my only non-coastal city in the whole game. Red dot has a fish for food and plenty of grasslands for additional cottages, while yellow is an even better version of red with two fish. Green's land was absolute garbage, but it pulled in two whales, crabs, and a marble resource that I previously lacked. Finally, blue dot had no food resources at all, so I planned to irrigate every flatland tile and mine all the hills for a production powerhouse, similar to Guimaraes. Now notice that I'm letting a few tiles be wasted on the east coast; ordinarily that would be taboo, but due to the total lack of food bonuses over there, the land just didn't seem strong enough to support an additional city crammed in there. All of the seafood resources hugged the western coast, so it was no coincidence that my cities did too. The land should dictate the dotmap, not the other way around!
During the following turns, I focused on ferrying more settlers, workers, missionaries, and defensive units over to North Island. At one point, I actually sent every worker from the main continent up there - that's where the need for new tile improvements was greatest! The Great Library eventually produced a Great Scientist, who was used for an Academy in Lisbon. Otherwise, things were calm and smooth sailing.
I had two elite maceman fighting a protracted war against several barb cities on the other island, which I consequently dubbed Barb Island:
No sooner did I raze Etruscan than another barb city popped up almost on the same spot! Nuts to that. The barbs also upgraded from archers to longbows at about this time as well, which dragged out the combat considerably. My City Raider maces could kill individual longbows (at about 80% odds), but then had to wait to heal up after each victory. I could have ferried over some more troops... but my carracks were already busy working on improving North Island. So I was content to grind the barbs into the dust slowly, over the course of several dozen turns.
Eventually I figured out where Suryavarman's army was heading:
Not me, fortunately! 
Hammuarbi was pretty pathetic in this game, stuck with a mere three cities, and I didn't expect the war to go well for him. I would turn out to be right...
But in the meantime, there were more important things for me to be dealing with. I could have researched Liberalism as soon as 950AD, but held off in the hopes of grabbing something further down the tree. However, if you look at the above shot, you'll see that my espionage was telling me that Willem was in the process of researching the tech himself. That meant I had to stop stalling and grab the darn thing myself! So I did:
I had already gone all the way to Economics (for the Dutch unique building, the Feitoria) and taken the Great Merchant there - this was not your traditional Nationalism slingshot! I took Astronomy so that my trade routes would reach over the oceans to my new colonies. With harbors and feitorias (Dutch unique building) everywhere, plus Open Borders with all civs, and not to mention the Great Lighthouse, I was making some serious moolah from trade in this game.
My warrior provided updates from the Babylonian/Khmer front:
Two longbows in Babylon? Yeah, I think we all know what's coming. The city fell the next turn, and Hammer soon became Suryavarman's vassal. That was a good result for me - there was less money to be had via trade should Hammurabi be killed, and Babylon's capture allowed Guimaraes' cultural borders to expand outwards and grab a spices resource! Mmmm, spices. 
When Lisbon produced yet another Great Merchant, I used him to fire off a Golden Age:
I do like the single Great Person Golden Ages; that seems like a very good addition to the game. Since almost no one thought that Golden Ages were worth expending two Great People (until they lost their value later in the game), that was a good sign that the Golden Ages were too expensive. I timed this one to help build Taj in Lisbon and the Forbidden Palace on North Island.
Not everything was fine and dandy overseas, however. Initially I didn't see much of a difference with my colonies, but as they continued to grow up to larger sizes, the maintenance costs started spiraling out of control:
Whoa! What the heck? What is with this "colonial expenses" BS?! 
It would be one thing if this were some minor addition, but just look at the thing! MORE THAN DOUBLE the maintenance costs from distance and number of cities. What a load of bull. No wonder people are posting at CivFanatics that overseas colonies aren't worth the effort, and archipelago maps are all but unplayable. Blah.
Let me be clear about this. So it's not enough that to build colonies overseas you have to:
1) Research Optics and Astronomy techs before your rivals
2) Explore the seas with caravels to find new islands
3) Fight off barbarian natives
4) Transport settlers, workers, and military units into the wilderness
5) Pay huge "distance" maintenance costs until a Forbidden Palace is completed
Now we're slapping a gigantic UNREMOVABLE colonial cost on top of all that?! Seriously, someone at Firaxis was on the crackpipe when they thought up this idea. 
I don't care if it's "realistic" or not, this is a TERRIBLE idea for gameplay! I mean, like it wasn't hard enough to set up colonies already? We need MORE obstacles in the way? It's like they're asking everyone to ignore everything but Pangaea maps. I sincerely hope that this will be eliminated in a patch, but I doubt it will be. (Firaxis seems to want players to "release" their colonies into a new vassal state - as if I'm going to do that after busting my butt to set the whole thing up in the first place!) What a huge bummer.
Anyway, those ridiculous costs made completing courthouses and the Forbidden Palace more critical than ever. (Too bad the FP doesn't remove colonial costs! Actually, that might be a kludge to alieviate the problem, if not solve it entirely...) I used some lumberjacking tricks to help it along:
Nothing like knocking out a quarter of the building's cost in a single turn with two chops! Anyway, the FP completed in Faro in 1405AD:
But as you can see, the costs IN MY FORBIDDEN PALACE CITY were still crazily out of whack. Even with the courthouse, the costs are still over 7 gold/turn. Seven! That's insane. Notice how the "Colonial Expense" is more than double all other costs combined. God, this system stinks to high heaven. Why do I have to pay TRIPLE maintenance costs, just because this city happens to be on an island instead of the starting continent???
*Sigh* 
Anyway, things remained peaceful and relatively uneventful. Here's my developing colony on North Island at the benchmark date of 1500AD:
Notice that I can't research at a rate above 60%, and in fact I'm actually losing substantial quantities of money even at this pace. That was largely due to my "colonial" costs; even though I had a lot of cities, they were all quite close to either the palace or Forbidden Palace. Distance maintenance costs were minimal - most of the penalty is coming from those unremovable colonial fees. In Civ4 1.61, I would have been able to manage 80% science here without too much trouble. What a drag.
And the Demographics. Pretty much what you'd expect, but look at my trade route income! (highlighted in gold) The first number is what you're paying out in trade routes, the second number is what you're receiving from them. Thus, a "low" ranking is actually really, really good. I'm pulling in a full 130 commerce/turn just from trade routes - equivalent to TWENTY-SIX fully mature towns! And remember that this is BASE commerce, which gets multiplied by libraries, universities, and the like. Now this is how to play a seafaring civ!
