The Spa at Green Valley Ranch is a dream. Even with a local's discount it's a little pricey, but worth it. I got a Swedish 60 minute massage and it was glorious. Essential oils, talented masseurs and calming atmosphere took the most ticklish person and brought her into a world of relaxation (that would be me).
Besides the massage services, the spa pool, gym and locker rooms are well equipped, clean and beautiful. Poolside food and drink service doesn't suck either.
Also the endless supply of pretzels and tea is a plus.