Keyholes are good - I had them at one point, but the male I had ended up being a bit territorial. another suggestion would be to get rainbow cichlids - these are the most peaceful cichlids I have ever owned - even when spawning they never did more than just chase curious fish away from their nesting site. Rainbows can be very pretty too - they tend to be a yellowish body with dark black lines and/or splotches, and will have a very nice bluish hue to their fins. you could probably do a pair of keyholes and a pair of rainbows, this way you have a little variety.