I'm going to disagree about that choosing method
Most mbuna cichldis (like those mentioned) are not good chocies for a small tank. Going to your lFS and just randomly picking out the ones you think look 'pretty' is very unreliable. You never know what you're getting, how aggressive they'll be as they mature, their potential size, not even what their diet might be.
You can put some yellow labs in though. They are a hardy cichlid to begin with and are more moderately tempered. A group of 5 with a single male and 3-4 females would be best and you can add a bristlenose or one of the medium-sized syno catfish as well. The other good thing is that they are insectivores in the wild so don't get 'malawi bloat' quite as readily as some of the others. They still do best on vegetable-based foods but enjoy brine shrimp/mysis supplements as well. This is good if you want syno catfish as they are carnivorous and can be difficult to feed with other (herbivorous) mbuna in the tank.
I'd like to point out that mbuna cichldis are also not your only choice. Nor do they have to be malawian. African cichldis range widely. Some of the tanganyikan cichlids would do very well in that size tank. There are julies you could try, for example. Then there's various shell-dwellers and don't forget the ever-popular pulcher/kribensis which is also african (though they live in rivers).
In your tank, I'd personaly go for shellies and some danios for the upper layers.
Also, if you aren't specificaly after africans, there's all sorts of neotropical dwarf cichlids you could put in there and you could even add community fish to it with most of them. German blue/gold rams, bolivian rams, keyholes, apistos - there's a multitude. Then there's angelfish that are also south american cichlids. There's also some slightly more aggressive neotropicals to choose from such as firemouths - just about - or the very aggressive, rabbit of the fish world, the convict.
You could even go asian and brackish with the orange chromide.
I know you said you wanted africans but you may find one of the other options more interesting.