Spas with reservation required

Adults-only hot springs resort on Miracle Hill in Desert Hot Springs with private mineral tubs, a Finnish sauna, salt room and 35 spa treatments.

A luxury day-pass wellness circuit inside Carillon Miami Wellness Resort, with sauna, steam, cold plunge and thermal pools in North Beach.

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.

Hotel spa at Agua Caliente Rancho Mirage with day passes for the sauna, steam room, salt rooms and private spa pool.

Adults-only resort spa in Sedona with outdoor hot tubs, steam rooms and a 30-treatment menu, open daily with walk-ins and day passes.