I was sort of in the spa when it was the FS. I had a massage, and was taken to one of the "overflow" treatment rooms upstairs on a regular stay floor - pretty weird padding up the elevator and down a hall in a robe and slippers with regular street-clothed guests.
Did get to use the pool after and it was very nice - even though it was supposed to be for all hotel guests, there were just 2-3 people there when I was there, all of them spa people (could tell from the robes).
We stayed next door at the ES and we really like that hotel for both the price and space. We also had dinner one night at the FS, which was very nice. Look forward to seeing the changes next time, too (we will again stay at the ES).