Round 4: 455 BC to 320 BC (9 turns)
A short round because I decided to follow BlueSoxSWJ's suggestion and just research the first few cheap techs and see what else cropped up.
I decided to fit in Sailing before Meditation and Priesthood. Besides hoping for trade routes, I also thought I might need some Galleys before long. Remember the 3.17 patch has increased barb ship activity.
As you can see, researching at 100% with all that gold was helping research. Unfortunately, I was going to go through that gold very quickly.
As many of you suggested, I reassigned the capital's tile assignments to emphasize commerce:
The Work Boat is only being built for exploration, after all, so it can wait. By this point I had also connected my territory with Arabia by way of a road north of Akkad, hence the new, enhance trade route.
Sailing didn't take long.
However, my trade routes didn't change.
So even though I had open borders with Darius, the barb city, and perhaps Saladin as well, are preventing us from having trade routes. Or maybe I need to find at least one Persian city, too. Anyone care to explain how it all works?
Shortly after this, Saladin discovered Alphabet.
Of course he's even more advanced than he appears. He had dye to trade, for example, so he obviously has Calendar as well.
No surprise, I'm at the bottom of the advancement chart...
And at the end of the round, I met another neighbour.
Justinian's Scout is north of Babylon, so I assume he himself is somewhere north of Saladin. Interesting how he has no religion yet.
I also finished a tech at the end of the round, having researched Meditation earlier...
And now I had to decide on my next target. Or, more to the point, come back here to discuss it more. Monarchy will take 10 turns:
Code of Laws, 11:
I'll be broke after 10 turns of research. But then again I have a stack poised outside that barb city, ready to capture it next turn, so that might just give me enough to research either tech and leave a little cash in the treasury so it isn't running on fumes. Oh, and I checked, and I can run the slider at 10% with a 2 GPT surplus. Yay me.
So as recommended, I stopped here so we can have a more informed discussion around which tech would be better to pursue. To provide more grist for that particular mill, here's a look at the map:
So there's a little bit of good news there on the happiness front: My exploring Chariots have discovered, down south, both furs and silver. I should have no problem founding a city there, although it has no food source visible, so unless something shows up in that fogged area to the NW, it will be an extremely marginal city founded solely to claim these resources... and fog-bust, too.
Right now, the best placement for a city down there would be 1SW of the silver, on a tundra hill; 1N of that tile is a forested grassland tile next to a lake, which would therefore be the city's only source of food. That would place the silver, the copper, and 4 fur tiles in the city's fat cross. Unfortunately it won't be able to work the silver mine and pay for itself until Biology, but having the resources (especially the furs, which provide the added benefit of being trading fodder) would be worth it, I think. (I can also place another marginal city 1E 2S of the southeastern deer tile to claim it and the copper, but that's a very low priority right now.)
And the gold/pig/fish site is still available; that would be the next city site, as I'd have to rush a Settler there to keep it out of Saladin's hands. The fur/silver site can wait a while, if necessary.
So there are three

resources available, though it requires founding 2 additional cities at considerable distance from the capital to claim them. Nevertheless, I think that argues in favour of Code of Laws as the next tech.
Here's a look at the domestic advisor to check on the city builds:
Once Akkad completed its library I began on a Christian Monastery. After that it won't have anything to build until CoL allows it to construct a courthouse, so I may switch to military temporarily. As I recall, some of you were suggesting settling the Great General there, which I haven't done yet. The monastery's culture will help stave off Saladin's borders, which are pushing against mine in that area.
Foreign Advisor, Relations:
Everyone's at cautious with me and is likely to stay that way for some time, unless and until someone else's religion spreads to me--or I spread Christianity to them. Zara pursuing that early religion was both a good thing and a bad thing; it distracted him from military pursuits and provided me with a potential shrine city, but because of my failure to construct any roads to Arabia (and, thereby, trade routes), it's spread to all my cities and has put me in a difficult diplomatic spot.
Resources:
So like I said, Saladin also has Calendar. I could potentially trade pigs to him for dye, especially if I can claim that eastern city spot for an extra source of them.
Info - trade income and civics:
Thus far, Darius is the only one running Hereditary Rule, and the Oracle apparently provided him with Feudalism (!) so he's the only one running vassalage. Everyone who's anyone has slaves, though!
Techs:
So although I'd venture that Darius is the most advanced civ, he currently lacks Alphabet. Everyone else has it--everyone but me, that is. One of the tough things is guessing what Justinian might be researching next. Hopefully it's not Code of Laws or Monarchy, but the AI does like those techs. That could be critical, as Justinian is the only leader besides Saladin who's currently open to trading techs. It would be nice if I have an expensive one that he wants.
Assuming I do get a tech that both Saladin and Justinian want, what should I trade it for? I was thinking of getting Alphabet from Saladin, and then maybe Iron Working and whatever else Justinian will part with--maybe Masonry. Of course, if I manage to get Alphabet, that would open up trading with Darius and would change the tactics considerably. One complication: Saladin currently lacks Priesthood and therefore cannot trade for either Monarchy or Code of Laws directly. I could gift him Priesthood if he still needs it at that point, though I'm loathe to do so.
Overall, though, I think the tech situation also argues in favour of Code of Laws. It's worth more than Monarchy and will therefore make better tech bait. In addition, the AI typically prioritizes Monarchy over CoL, so if Justinian is pursuing one of our next two chosen techs, I'd lay odds it's Monarchy. On the other hand, CoL might still have a religion available with it, which may also make it attractive to the very Spiritual Justinian. Hmmm...
The Power graph:
This is only moderately worrisome at the moment, but I'll need to keep an eye on it. Everyone else's power has climbed and if I'm not careful I'll be left in the dust and look like a tasty treat. I haven't seen too many barbs from the south or east thus far, but with all that empty space I know they'll be coming.
Demographics:
Dead last in almost everything, but that's par for the course at this point in the game. The one bright spot is land area, where I'm in the middle of the field.
So as I said, I think I should pursue Code of Laws next along with founding those two cities. Combined, they'll raise the happy cap by 3, and double that once I have forges and markets. I can then trade CoL around, adopt Caste System to run more scientists or merchants as needed, and of course build cheap courthouses, especially in those two distant resource-claiming cities I'm eyeing.
But as always, I look forward to your own views before proceeding.