I think 2Fort is ok but pl_goldrush, cp_dustbowl, or cp_badlands might be good.
http://tf2wiki.net/wiki/Maps I played on our server with the bots for a bit ...and they suck! The bots can't play ctf, they seem to just end up running around in the other teams base trying to spawn camp. If we had people on the server the bots could fill a few slots. But if we want to fill the server with bots maybe we should use the maps that support them."koth_viaduct, koth_sawmill, and koth_nucleus."
Since this is a beta test, the TFBots are only functional on these King of the Hill maps: koth_viaduct, koth_sawmill, and koth_nucleus. They don't understand the rules of multiple point capturing, cart pushing, or flag getting... yet. There's also no interface in the game to accessing them yet (we'll add one in an update shortly), so you'll need to access them manually.
http://www.teamfortress.com/