Spas with reservation required

San Francisco, California

Adults-only Russian bathhouse in San Francisco's India Basin with steam rooms, cold plunge, rooftop deck and a café, open daily except Tuesday.

Scottsdale, Arizona

Hotel spa at the Inn at Eagle Mountain in Fountain Hills with sauna, steam room, pools and a $69 60-minute massage as its signature treatment.

Minneapolis, Minnesota

A St. Paul wellness studio in Macalester-Groveland offering infrared sauna, float tanks, salt therapy and cold plunge by reservation, adults-only, day-pass