I would love to fill it with Lake Malawi African Cichlids. Just to THINK about the possibilities. OR, schools of 20 of many many different community fish. Oh just thinking of all those Tetra's gets me giddy.
I would hire Travis Simonson to create a fabulous planted FW tank complete with dramatic drift wood sculptures. It would feature a few large schools (40-50 fish each) with various other fish as filler.
7 Australian Rainbowfish
5 Cherry Barbs
1 Pleco ("Plato")