If you can find one, a 40 gallon breeder tank will give you the most floorspace for your buck
Get one of those metal reptile screen tops and you'll be set!
Yes i have Three in total lol theyre my favorite! I bet the "display" 55 i had had just about the same bottom sq footage as the 40 breeders do. But then i think a 55 would better fit Cosmosue's needs in her office...