What does the enclosure look like?

In that size enclosure....you basically have two options:

1) Something that gets big OR
2) Something that needs alot of space

I would go with the second option and get a nice group of ackies or one medium sized monitor lizard. That way you do not have an animal you can not handle on your own, but you get animal that is cool to watch and will make full use of a large enclosure.