After wanting to go for years I finally made the (heh) trek there last weekend.
Freakin' amazing!!
We paid the extra $25/person for the photo tour. Well worth it and I strongly recommend anyone who visits to do that. You don't see anything extra and the tour isn't any longer but it is a private tour for your group. So for me it was just me and my wife on the tour. What that means is you have more time to look at and take pictures of things and have pictured taken of you because you don't have to get out of the way to give someone else a chance. You also get to sit in a few places (like at the desk in Kirk's quarters) that people on regular tours don't get to do.
I wish I could remember the name of our guide because she was a total TOS geek and did a superb job.
Now I want to convince some of my other TOS fan friends to go and I want to go with them, both to see the sets again and to be able to watch their faces when they walk into some of those rooms.
Definitely something any serious TOS Trekkie should try to do IMHO!