I'm a couple days late here, but I figured I'd post this here in case anyone else is wondering about the studio tours. I took the tour of Paramount back in January and thought it was fantastic. The tour was about two hours long and cost $40. We got lots of great history about Paramount, and were able to walk on several stages (including The Doctors, Community, and Big Time Rush). It was very neat to be able to walk on to the set of Community, which is one of my favorite shows. I was able to get an upclose view of some of the props used in the show (including the diorama), and also see the posters on the walls upclose.
While we were there, we actually saw one of the cast members from Glee (Becky) being driven to set in a golf cart--she was wearing her Cheerios outfit, and was all smiles when we recognized her. I also saw Mark Salling from Glee when I was arriving at the studio--he actually stopped his car coming out of the studio so I could cross in front of him. I was surprised when I turned to smile and wave my thanks as I would to any driver who let me cross in front of them, and then realize it was an actor from a show I watch. Later, Chevy Chase drove by us in his car.
I thought the tour was excellent, and well worth the time. Just remember that it can vary from tour to tour. If they are filming on certain sets, you will not be able to go on them.