There are some golden mantellas on Kingsnake.com right now. I also have an empty 18x18x24 and originally got it for dart frogs, but could never decide which kind. I've been leaning towards some fine spot leucs or some orange terribilis. Something with a loud and cool call. Either that or some Milky tree frogs or some type of waxy monkeys. Too many choices so the tank sits empty til I see something that can't be passed up.

Just go with your gut Mike, go to some local reptile shows and wait for something to strike your fancy. Meanwhile you could just set it up.