The spa at Stowe Mountain resort. You can arrive one hour before and stay as long as you like post treatments. They even have a rinsing room dedicated for scrub treatments. I mean you do not leave the table and end up on dry clean linens post treatment. It was spa nirvana. Close 2nd was the mandarin in Boston on boyleston. I think their spa was 25k s.f. Of sauna, steam, pool, whirlpools, etc…