We had a great tour, and a funny enthusiastic tour guide. The tour was fun, and they give you a cool lanyard ticket for the tour that you get to keep.
We saw pretty much all of the areas that are publicly accessible. We also got to see under the stage (there is a crazy elaborate hydraulic system that can move things around). We also went through some rooms that I assume are normally off limits to see costumes worn by the Rockettes. There is a VIP room for performers.
There is an odd moment in the tour when an actual current Rockette is brought out, in costume to answer questions. They do not allow photos to be taken at this time, but if you would like to get your photo taken with the Rockette, they will take it and sell you a copy. This part of the tour had some obvious awkwardness to it. Most people in our group passed on the photo op.
The tour over all was great! This is an amazing venue, and it was cool getting to explore the place, even without seeing a show there.