The only one I can think of offhand is "Faces", which is at the Wexford shopping plaza, about halfway between the Disney resort and Sea Pines Circle. I've never been there, but I've seen it advertised.
I would call the resort directly and ask them if they have any recommendations, just to be sure.
I believe the major hotels have day spas--or are in the process of adding them. I can't quite remember which, but I read an article about it in the local paper last summer. Try calling the Westin and the Hilton.
Some other places to look at: (haven't tried these personally though)