I can't really think of anything that would 'live' in the holes. Like Pure said, some may use it if it's the closest or only place to hide when they feel they are in danger, but that would be about it. The closest thing I can tell you is N. brichardi from personal experence. I had a piece in with a breeding pair and on their first few spawns they did use the holes in the holey rock for a breeding cave. But once they got a little size on them they could no longer fit and had to move elsewhere.
Also if a cichlid did live in it, you have to keep in mind that for the most part they are going to be very teritorial. So most likley if some did take up in the rock, it would chase all others away and claim it for itself, possibly leaving many fish 'homeless'.
The dwarf julies would be great to keep in general. They do have some color on them, and thier personalities just can't be beat.