If you're open to other herps, with a 75 you could create an awesomeamphiuma habitat, or Necturus.
Sticking with reptiles, ackies are #1 on my list, and you could keep a group of them in a 75. Tokay geckos are awesome, and you could house a whole colony of them. Or giant day geckos. Maybe mountain horned dragons? I knew someone who kept those years ago, and he loved them. Said they had more personality than beardies.
You could do a really great planted vivarium, or a paludarium for any number of species, if that's something you're interested in.