The National Zoo in Washington, D.C. did an extensive study on this in
conjunction with several other zoos, including a zoo in Dallas, I believe.
From their evaluations they created a new exhibit, and have probably done
post-evaluative work on that.  Contact Dale Marcellini, Curator of
Herpetology for more information.  I believe the study also involved Zahava
Doering, the Smithsonian's evaluator(as the zoo is part of the Smithsonian
Institute).
No need to reinvent the wheel!
Good luck.