Took a 250 class @ Gunsite in March'01 and was very please with the instructors and the place in general.
Am signed up for a class @ TR in July and another in November. I have many friends who have gone to TR and they all speak highly of the place.
Both Gunsite and TR are equally good, with small differences between the two. You won't go wrong by going to TR and you cannot go wrong going to either/both. It really depends on which is closer or eaiser to get to.
Gunsite is nice because you can go party in Vegas after your done, but it's hump to get there from where I live and gets expensive with airfare and rent-a-POS, then hotel, ect.
TR is close to me and I can drive, so. FWIW, they both honor each others classes for pre-req's.
But, I have a friend who's been to TR eight (8) times and she (yes, it's she !) speaks VERY highly of the place.