All male African tanks can look pretty cool, plus you won't have to deal with a bunch of fry. Mbunas especially can be prolific breeders.
Not usually a good idea to mix New World and African cichlids. Different behavior patters, different water parameters, different feeding requirements, etc. In fact, I recommend not even mixing different lakes, or regions if you go with Africans.
New World cichlids are S Amer and Central Amer cichlids. Given the size of your tanks, I might recommend New World cichlids as well. There are a lot of very colorful dwarf cichlids which are fairly peaceful from these areas. Check out Rainbow cichlids, Apistogramma species, Rams, Firemouths . . .too many to list. I agree with V227, except about Jack Dempseys. They may get too large for your tanks. However, the electric blue variety tend to stay a bit smaller, so could possibly work.