I'm late coming to the party I guess. I keep cichlids and have for awhile now. I have a few suggestions to share with you.
1) I would suggest perhaps going with simply one type of cichlid if this is your first experiment with them. Mixing labs with peacocks or mbunas can work but it's a little tougher than you would think and you will have plenty to deal with just learning how to keep this fish. It's not like keeping regular community or even semi aggressive fish, there is a learning curve, and it can be steep at the beginning even if you do all your research.
2)Along the same lines I would recommend keeping mbunas over peacocks because they are easier to maintain, less aggressive, and cheaper to buy---you will have losses once they hit adulthood if it's your first try at this.
3)Of all the African's I've kept or seen by far the best has been the Acei. I absolutely love them. They're beautiful, they're well tempered, they are very social, and they are just overall the best group of fish I've ever kept. I would also recommend Psudotropheus Salousi.
females are a bright yellow all over
males look like females until adulthood then change to this
http://www.tropheus.info/riftlakes/cichlids/pseudotropheus_saulosi.html
4) If you're keeping fish that grow to 8" I wouldn't keep over 6 of them in a 55 gallon and for 5" fish I wouldn't recommend over 8-9. Everybody talks about overcrowding reducing aggression. I have found this to only be true in tanks over 55 gallon.
5) If you have at your disposal a smaller tank, like around 29 gallon, I would recommend using it as a growth tank until they start to hit adulthood and exhibit lots of aggression. It can really cut down on aggression if they are moved to a different larger tank and have to set up new territories. If you don't it's really no big deal but I thought I might mention it in case you did.