Spas with hotel guests only

Houston, Texas

A Four Seasons hotel spa in downtown Houston with three treatment rooms, a couples' suite and rooftop pool access, open to day-pass guests.

Milan, Lombardy

A luxury hotel spa inside Four Seasons Hotel Milano with a 14-metre pool under a vaulted ceiling, sauna, gym and private suites for couples' treatments.

Washington, D.C., District of Columbia

Hotel spa at Four Seasons Washington, DC with a private contrast therapy room, pool, and an adults-only, couples-friendly treatment menu.

Orlando, Florida

Adults-only resort spa at Four Seasons Orlando, open daily 9am-8pm, with 12 treatments, couples' suites and access to a 21+ pool for guests booking a 50-minute

Boston, Massachusetts

A luxury hotel spa in Boston's Back Bay with a Crystal Steam Room, Vitality Pool and private couples suites, open to adults 18 and over.

Chicago, Illinois

A hotel spa on Trump Chicago's mezzanine level offering day passes, 22 treatments, a heated pool, steam room, sauna and fitness club; minimum age 16.

Miami, Florida

Adults-only hotel spa on Belle Isle near South Beach with a hammam, sauna, ice room, infinity pool and a day pass option for non-guests.

Palm Springs, California

A 16-room adults-only hotel in Desert Hot Springs with three natural mineral-water pools fed by a 350-foot geothermal well, plus a small on-site spa and

Rogaška Slatina, Savinjska

Wellness center at Grand Hotel Rogaška in Rogaška Slatina, Slovenia, with pools, saunas and fitness; day pass available by reservation.

Auckland

A family-run rainforest resort in the Waitakere Ranges near Auckland offering a day spa, private yoga and free hiking and biking trails.

Orlando, Florida

A hotel spa at Waldorf Astoria Orlando offering massages, facials and a Himalayan salt room, open daily 9am-5pm with day passes available.

Houston, Texas

Hotel spa at Hotel ZaZa in Houston's Museum District, with massages, body treatments, infrared saunas and day-pass access to the pool lounge.

Banff, Alberta

Luxury hotel spa inside Fairmont Banff Springs offering thermal pools, steam rooms and treatments, open daily with day passes for non-guests.

Brežice, Posavje

A large thermal water park in Brežice, Slovenia, with a year-round indoor pool riviera, an adults-only sauna zone, and seasonal outdoor slides.

Palm Springs, California

Boutique hotel spa in Desert Hot Springs with two natural mineral hot spring pools, day passes, and overnight rooms that include breakfast.

Las Vegas, Nevada

Adults-only hotel spa at Green Valley Ranch in Henderson, open daily 8am-8pm with day passes available to non-guests.

Palm Beach, Florida

Indoor-outdoor luxury spa at The Breakers resort in Palm Beach, open daily 9:30 AM to 6 PM, mainly for hotel guests and club members.

San Diego, California

A rooftop hotel spa in San Diego's Gaslamp Quarter offering treatments and a 24/7 fitness center, open to hotel guests and day-pass visitors.

Leukerbad, Valais

Thermal baths inside a 19th-century hotel in Leukerbad, Valais, with mineral-rich pools open daily from 9am to 8pm.

Vals, Grisons

Peter Zumthor's quartzite thermal baths in Vals, fed by a 30°C mineral spring, open to day visitors as well as hotel guests.

Scottsdale, Arizona

Adults-only resort spa in Fountain Hills with sauna, steam room and outdoor pools, offering day passes and an amethyst facial as its signature treatment.

Carson, Washington

A clothing-optional, adults-only mineral hot springs bathhouse in Carson, Washington, with a $12 day pass and a $30 bath-and-wrap treatment.

San Francisco, California

Adults-only hotel spa in Sausalito, California, offering day passes alongside yoga and a restaurant on site.

Orlando, Florida

A hotel spa at Conrad Orlando offering treatments to hotel guests and day-pass visitors in an upscale setting.