I like Cons a lot. I've hears they will kill anything else in the tank though when breeding. I would be up to my eyeballs in baby cons with three pairs. lol I'll add it to the list though!
I would deffinatly do one or two bluegill. I think you would be alright with two for a while. This way you will save on heating costs too. I have a bunch of bluegill and they are such cool fish. May not be anything great to look at but they sure are fun.