I've booked the salon inside the main lobby of the GF - Ivy Trellis is the name of it. They do hair and makeup only. If you want nails and other services, you go to the GF spa. I think Ivy Trellis is technically not run by Disney but it's convenient and I'm going to be way too hyper on my wedding day to sit in my room while 1 person does hair for 5 of us!!! At Ivy Trellis they'll do 2 at a time and we get out of the room.
I have to say - for me a part of the fun of a DIsney wedding is getting to walk around with my veil and then my dress and get some extra attention!