lurker's comment: As one of the resident meddlers, I can't resist the urge to make a few comments.
Civ Choice:
If you're going for conquest, and it looks like it at this point, it can be accomplished with any civ. Some, however, will be easier than others. The question is how far out of your comfort zone you want to be, and how much of a learning experience you want this to be.
Early UUs may guarantee you a despotic GA. Knight replacements can time GAs very well, but you may want an even later GA, just so that you don't entirely overwhelm the poor AI civs when it comes in. Late (cavalry, industrial or modern age) UUs frequently come so late that they don't have a great impact on the outcome of the game, but that may be better from a learning standpoint.
Babylon is a nice enough civ, but the religious trait probably won't be all that helpful to you. The scientific trait is nice for the freebie techs, and the cheap libraries. The Bowman is decent, but it's almost going to guarantee that you get a despotic GA, though.
The Iroquois are a frequent favorite in the "Favorite Civ" threads that crop up, and for good reason. Agricultural and Commercial, they start with Alphabet and Pottery. Nothing wrong with having early granaries, extra food and starting the game one step closer to pulling off the Republic slingshot, not to mention early curraghs for exploring. The MW, of course, can rule the Ancient Age, but runs the same risk of a despotic GA. Now, if you get into republic before you start using them, that's not a problem.
China is another one of my favorites. Militaristic means cheap raxes and early archers. Industrious is one of those generally useful traits for any victory condition. The Rider is the earliest possible 3-move unit. You can get to your enemies a whole lot faster than they'll get to you. Reminds me of an old commercial: "Reach out and touch someone."
I also like the Romans, but I think I like them more than most of the players better than myself. The Roman Legion gets an extra defensive point (3/3/1), so they can be awfully tough to kill when they show up on the scene, but many of the really good players would rather pay the extra shields for an extra offensive point, rather than a defensive one. Commercial, on the other hand, means that more of your cities can skip building courthouses and concentrate on military units instead.
The Celts: Another agricultural civ, with religious. The agri trait is very powerful in C3C. More food=faster growth. More people=more gold, more shields, more units, more towns. I'm not a big fan of religious, but the Gallic Sword is hard to argue with. At 3/2/2, they match the Ancient Cavalry, and you can build them in several cities all at once (assuming you have iron).
The Ottomans were mentioned earlier. Again, scientific and industrious. Cheaper libraries and the freebie techs are nice and the Sipahi means that you won't have to worry about a despotic GA. At an 8 attack (IIRC), you should be able to slap the AI around at will. The nice thing (from a TDG perspective) about having the later UU is that you have to get through the AA (and if you choose the Ottomans, most of the MA) without getting your GA, so that part of the game is "uncluttered" by the GA.
Wonders:
I'd suggest staying away from the Ancient Wonders, especially the GLib. I'm going to assume that all of the players have read the 4 Rules of Wonder Addiction. I think you'll be surprised at just how fast expansion can go if you really focus on workers, settlers, and military. When you've only got (for example) 8 towns, 400 shields is a huge investment.
Just my $0.02. Good luck!