Bronze age: Total War
Play as minoans, hittities etc, plus pharaonic Egypt like in RTW
(I'm not a history freak, so I'm not sure if this will be workable)

Polis: total war
Play as a Greek city state, battling naturally other city states. Diplomacy should probably be more refined for this game. In the TW tradition, give it an X pack called Macedonian invasion ;)

Viking invasion
Already an X pack for Medieval, but I think the period is interesting enough for a a stand alone game.

A personal dream of mine is to fuse the games Stronghold (original- haven't played the sequel yet) and Total war- build your own castles as effectively as you can design them, and defend them from attacks from AI players on the campaign map.