All of the suggestions so far are good. Ideally, IMO, a tank this size deserves the absolute king of fresh water fish - discus. Nothing else comes close. But as most long time fish keepers know, experience and dedication are needed to maintain healthy discus. Although, a planted tank is probably not the best environment for discus on second thought. But, really, for you, there are no limitations. I would be a bit overwhelmed by the possibilities.