Tokays make amazing display animals. 20 tall is a stretch depending on how big it is. A uroplatus would be strictly for someone with tons of prior gecko experience. They're super tough to keep. Supposing that amphibians would be ok, I don't see why not to go for the gold :) red eye tree frog. That is probly the ultimate in display herps.
If you're aiming for the ultimate display viv, with live plants, ect. You're gonna wanna go with something small and tropical. I bet you could do real well with some red eyes.