A Republic has no Military Police so having units garrisoned in cities that can't be easily reached by the AI is a waste.
Yeah, and I was so concerned about a land invasion from the Arabs that I forgot to guard my coastal towns from a sea invasion from Egypt (which I fortunately fought off).
Culture probably isn't an issue on Regent, but at higher levels you'll want a handful of units in each city whose first cultural expansion is intersected by an AI's city's first cultural expansion (intersecting BFCs, generally when their and your cities are closer than OCP) as this will protect against culture flips. Coastal cities should have some fast units in/around them too, I try to have a small stack available that can defend several cities at once.
BFC?
Also, since I'm playing for an 80K victory as a backup to the Spaceship in case resources become a problem. So far so good, except there's so little coal worldwide, and in inconvenient places where it
does show, that I can't put in railroads without invading somewhere, and I've gotten to the point where it may very well not matter - I could very well win with no rails at all. I could invade the Americans for it, but I don't want to waste my time (
this game, anyway ... I've done it before) on a war that ultimately will just distract me from the long-term goal.
I like playing peaceful spaceship games as well, using the AI as trading partners will help speed the game along ("zero turn research is faster than 4 turn research"). On lower levels, you'll probably need to create your own trade routes with each civ, and they'll probably go through unclaimed territory.
Indeed, that's sometimes a problem - especially this game, which is light on both luxury and strategic resources even for a Small map.
Keep a unit capable of cutting that route and some workers to reroad it if you can, this allows you to control AI-AI trade (my trade route with the Greeks/Ottomans heads through Byzantine territory then unclaimed territory before entering Greece and the Ottoman Empire, when I finished that road, the Greeks traded all their excess luxes and resources to the Byzantines. I simply cut and reconnected the route to end their trades and allow me to initiate my own.).
Now
that's something that hadn't occurred to me. Of course, since no one has any extra Coal that I can hook up (IIRC), which is the thing I need most at the moment (Uranium's next, once I get Fission 2 turns from now). Hopefully I'll have that ... plenty of Rubber and Aluminum, at least, for the Ship. Now I just have to make war on the Incans to steal their Uranium.
Also interesting in the current game ... I have culture flipped seven towns - 1 from Egypt, 2 from the Arabs, and
four from the Americans. That's way more than ever before.