Pseudotropheus saulosi are a very neat little malawi cichlid that isn't AS aggressive, has blue/black stripe and orange fish in one colony, stays 3" or a bit more, and has a ton of variation in the group. While your prime directive isn't breeding, the fish are going to breed anyway, unless you can specifically pick out only males for the tank. With P. saulosi, you wouldn't have to remove fry, but if you did have survivors, they're usually very easy to market.
If you go with an all male tank, you can spread the aggression by overstocking a bit and have a very colorful display tank, also. Depending on the type of tank you do, the rock work can definitely help the fish live through problems. In an overstocked tank, the rockwork isn't as necessary, due to the fish not being able to find the fish repeatedly to torment.
Barbie