go for africans
i think with your size tank and your desire to get a big variety, you should dump the idea of americans and get africans, i like africans better, more color, around the same personality, and some are really mean if you like that. you could go for cobalt zebras, or pseudotropheus, or both, maybe like 3 or 4 of each in a 45, just ask questions before you purchase. or you could do tanganyikans and have an even large variety and more biodiversity.
go for the Africans, Americans really need huge tanks in general.