Okay, so some big changes have happened. A friend gifted me an 80 gallon, basically a custom-built 75 that's an inch taller (48x18x22 as opposed to 48x18x21) so I have enough room for pretty much whatever lepomis species I want. My LFS sometimes gets bluegills in with their goldfish, because the manager is an experienced native keeper himself, so I'll probably be going with a bluegill.
Now my next question is, can I keep central stonerollers with the bluegill if I get them all around the same time? How many do I need for them to be comfortable? I've also read that they like cool temperatures, but is this cooler than room temperature? The tank is in my basement and I'm going to guess that it hardly ever gets above 70 down there.
I think you'd be better off with a smaller lepomis species; green sunfish are much more common in home aquaria for example. 70 degrees should be fine for any lepomis AFAIK.