I have a 150 community that has 3 cichlids-an oscar, a severum, and a single geo. Usually people recommend keeping geos in groups, and I think with some more skittish species, it's probably a good idea. The one I have is a male Geophagus sp. "Bahia Red" (originally had a female too until he suddenly turned on her) and he does fine by himself with the other bigger cichlids. So, a geo like a "Bahia red" (or the very similar Geo. brasiliensis) might still be a possibility.
Sevs are also pretty cool fish, although mine was really shy until I added the oscar (then he quickly started mimicing the oscar and rushing out to be fed). Another option would be a Uaru. Right now I'm growing out one of these guys to add to my cichlid community too. They aren't bright colored, but they have a pretty cool, unique look to them.