Have you considered Mesonauta sp.? Festivum won't always lurk around the top levels, but they're gorgeous fish, photos do them no justice, and they'll get to a decent size.
You could always look at Herotilapia Multispinosa... AKA the Rainbow cichlid. I had a group of 6 Red head Tapajos in a 55 with a trio of Rainbows and it worked out great. Both lower on the cichlid aggression scale and tend to save the aggression for their own species. Also will stay about the same size as the geos and you can get some amazing color out of them.
Herotilapia Multispinosa looks sweet! but maybe some with a more intense coloration that does not have red/orange look to it...to much of that in my tank already with the parrot trying for a different color...sorry for being to picky...lol