Most South American cichlids must be the only species, or even the only fish in the tank. Most Africans, especially Malawi cichlids, are fish who enjoy a large school, with many species. Tanganyikan cichlids can be a little feisty between species sometimes.

South American species tend to be larger, whereas you will find a huge variety of Africans that stay less than 6 inches.

South American cichlids need more water maintenence. Softer water, lower pH. Africans need harder water and aren't usually as sensitive.

I suggest you take a look at the cichlids on liveaquaria.com. http://www.liveaquaria.com/product/categ.cfm?pcatid=830 see if there's anything you'd really like to have. Then you can work the rest of the fish around that species.