Australia's Outback Stations can be addicting to build, just so you can have a big continental fence. It's soothing. Keep in mind, you get 100% unit production for liberating conquered cities as well as when opponents declare war on you. I love how flavorful each civ is!
Macedon and Persia are out today, and of course my gaming computer is in the shop for blue screenitis. They both look great. Persia's an infrastructure powerhouse that gets +2 gold for internal trade routes and roads that are one era advanced, so it's good to spread the traders around. His surprise attack ability lets you scoop up forward settled cities and quickly incorporate them.
Macedon is kinda scary. Two unique units aside, Alexander gets tech/civic boosts for conquering cities with certain districts built AND gets science whenever he builds a unit with his barracks replacement. And criminy, no war weariness!
Civ forums are talking about how the AI is much better for attacking cities. If they keep these quarterly updates, this game is going to be unbelievable by the end of the year.