I've been to Four Seasons, The Carlyle in NY, Banyan Tree, Ritz Carlton....etc, but this is one of my top two spas in the world. Everything is done to perfection and the amenities are above and beyond. The price of treatments covers your admission the spa, so plan on spending an extra hour enjoying the lap of luxury with pools, sauna, steam, and showers.
The therapists are incredible. I have been to the salon and the spa several times and I've always been blown away by the techniques and precision that the staff has.
Bite the bullet and get a treatment. You only live once and you could be doing much more indulgent things in Vegas, right?