I don't know what the terminal is like, but they have a first class overlook next to Rwy 18C/36C. I've only been there once, and I had a rental car, so I don't if you can get there easily on a short layover. With your layover, you probably won't have time to visit the Carolinas Aviation Museum at CLT either.
I am moving to CLT this summer for my job, and I'll get to spend some more time checking out the spotting situation. If you don't get any other info before your visit, drop me a note and I'll let you know what I discover.
KC-135: Passing gas and taking names!