This is a pretty open ended question...
So instead of telling you what to get, just a few things to research.
Planted- Low Tech or High Tech? Low tech doesn't limit to terribly, just no diggers or cichlids that have decorating preferences. High tech usually limit you to smaller schools of ornamental fish. Think cost, low tech will run you lighting (1-2 wpg) and maybe some "catch all" ferts. When you think high tech you're thinking heavy duty lights (4+ wpg), co2 (and no that crappy DIY won't work for a tank this size!), ferts. plants, substrate, etc. Discus look wonderful in any planted tank, as do angels, etc.
Specimen or species tank for a slightly large monster (y'know, oscars and stuff)
Rift Lake-
Tanganyikan, Victorian, or Malawi. More rockwork as a background (less work!).
I have only kept tang. I school of cyps with some bottom dwellers (synodontis or even shell dwellers would be cool).
Research different biotopes. I have a Rio Ucayali (Think ecuador) bio-tope. Here your research can go farther than just fish websites. Look up what the area looks like, then research water chemistry and fish that live in it accordingly.
Reef? (Boo!)
Coldwater and natives are another option (while not as popular, can be just as awesome).
The options are endless, the most important thing is research!
