I went there for my gf's birthday.
We were a group of 9 people. Everyone had a massage and a facial. My only criticism is that the massage was great but unfortunately I felt a bit rushed out of the facial.
We visited on Sunday. It was quite packed. Better to visit on a weekday.
The Four Seasons were helpful in assisting me while I organized this spa day for our large party. They also coordinated with dbar and Cafe Boulud.
I would surely go back.