Wow!
Thanks for all the input! Looks like going African is probably my best bet. I'm starting to form a plan in my head for things I like. I do like fire eels, I just didn't know that they were African. For some reason I always thought that they were South American. :/
I like the big mormyrids, but I think that I will probably avoid them for the same reason as I'd avoid emperor cichlids: I don't want anything to be a threat to Billy. I feel that the bottom dwellers are going to be safe and won't threaten billy, but I'm wanting to be very careful with fish that will actually be in the water column. Billy will be the only big fish swimming mid-level I think. I do have the ability to maintain the community while having various crown jewels in the tank as the main fish die of old age. This tank should keep me going for a long time.
I'm really liking some of the tilapia and Distichodus I'm seeing. I'm gonna have to do a lot more reading up on this, but things seem to be coming along better than I had hoped.