All I can tell you is that I had a rediculous experience at the Grand Floridian spa, so I don't recommend this place.
First of all, I'm 99% sure that Disney leases the GF spa to an outside health & fitness company. Disney does not run this spa, nor do Disney cast members work there, and believe me, you can tell the difference.
When I arrived for my 1/2 day treatment, there were a few girls at the desk fooling around. I stood there for a few minutes, then one of them finally said, "can I help you?". She led me back to a room for my massage. The room was beautiful and clean, but the masseuse (sp?) really played the "hard sell game". I really wasn't interested in buying any of the products, but she insisted on telling me that I was making a big mistake & that I should buy their products. After a while of this, I finally said, "I have more cosmetics at home than I know what to do with....please, don't try to sell me this stuff". She became a little huffy and didn't say another word for the duration of the treatment. That was fine with me, but my massage was kinda ruined after that. Afterwards, she led me to an area where I could shower and walked away in a huff.
I know this is probably an isolated bad experience, but I've always heard that the spa at the Disney Institute was actually run by Disney, so I'll go to that spa next time!