I am not too inclined to do that type of tour, but if I did I would use the sag service. I consider that type of ride to be more of a rolling party than what I think of as a tour. Nothing wrong with that if it is what you want though.
I've never heard of the sherpa service though. How well that would work would depend on how good of a job they did.
Last edited by staehpj1; 12-29-10 at 10:20 AM.