I have been to both spas. I did not like the mani/pedi area at GF at all. The stations were crowded together and it was noisy; I listened to the conversations of the other guests getting treatments there so I didn't find that relaxing. I have not had a mani/pedi at SSR so I can't say what that was like. I've done massage and facial at both. I liked the therapists much better at SSR but it could have just been the individuals I got at each one. The treatment rooms/atmosphere were equal to me, one was not better than the other.
To me, going to a spa always feels like a treat and I wouldn't turn down the opportunity to go to either spa!