Back for a little more help...
The Rotkeil has established itself as the tank boss. There's no serious aggression towards other fish, but it does chase the Angels out of its way occasionally. The only real aggression problem I've had was Lemon Tetra fratricide. I returned the two aggressors to the LFS, but they killed/mauled 4 of their shoal. The Angels are clearly the stars of this tank. They're nearly inseparable at this point and are both very active, interactive with us, and outgoing.
The Rotkeil's a moody little snot -- one day he hides from everything, the next he's taking flake food from my fingers, but we like him. I thought about getting another 75 to move the Rotkeil to and stocking it with an EBA and Colombian or Congo Tetras. I'd replace the Rotkeil in this tank with a couple of Bolivian Rams or other dwarf cichlids. My wife suggested a 6' tank instead, which definitely expands my stocking options for another tank. Cool wife.
I hate looking at crowded SA/CA cichlid tanks, so I'd like a balance between an aquatic desert and an overcrowded water prison.
I'm looking for mid-size (under 12"), non-psycho cichlids as the big guys in the tank with tetras (or maybe barbs) to fill it out. Would the Rotkeil, an EBA and a Chocolate Cichlid work in a 125? I've read mixed things about the Chocolates, but the rest of the fish I've considered (Uarus & Geos mostly) seem to be best kept in groups or pairs, which I don't really want.
Thanks.