This is the mother of all spas.
OK, maybe I'm exaggerating. But it's by far the nicest spa I've been to. This was actually my FIRST spa experience and going home to Scottsdale Arizona (which isn't exactly a slouch in the spa department) I haven't found a spa yet that can measure up to Spa Mandalay.
The spa is very large, with a reception room with refreshments, magazines and flat screens, a quiet room, a sauna, eucalyptus scented steam room (I think this was my favorite part), and the piece de resistance, their cold plunge/warm pool/hot tub room. It's women only (at least, on MY side! I assume they have the same for men) and literally there is everything you could want. Cold sliced cucumbers for your eyes and icy cold washcloths? Check (and perfect for a hangover, incidentally). Showers and a sink area filled with literally everything you need to primp, from perfume to hair dryers? Check. A locker room so huge that there isn't anyone changing around you? Check!
My massage was great too! But what truly knocked me out was the spa facility. I swear, I'm going to go here EVERY time I go to vegas, even if I just get a day pass and just veg out in the spa for few hours :)