Spas with reservation required

Santa Fe, New Mexico

A 16,000-square-foot adults-only hotel spa at Hilton Buffalo Thunder near Santa Fe, with separate men's and women's saunas, steam rooms and whirlpools.

Nashville, Tennessee

Upscale day spa in Franklin outside Nashville offering facials, massages, a salt room, infrared sauna and hydrotherapy tub, open daily by reservation.

Houston, Texas

Luxury day spa near Houston's Galleria with massage, facial and body treatments, a salt room and infrared sauna; reservations only, no walk-ins.

Charleston, South Carolina

A 52-treatment luxury day spa in Mount Pleasant near Charleston, with Vichy showers, couples suites and a $370 signature package; reservations required.

The Colony, Texas

A day-soaking spa in The Colony with mineral pools at varying temperatures, seven saunas, cold plunges and a poolside café.

Glenwood Springs, Colorado

A natural geothermal vapor cave in Glenwood Springs, Colorado, where visitors steam in ancient rock chambers and add massages, mineral baths or body treatments.

Park City, Utah

A reservation-only day spa in Sandy, Utah, built around scalp spa treatments, plus sauna, steam, cold plunge and thermal pools.

Dallas, Texas

Hotel ZaZa's spa in Oak Lawn offers massage and skincare treatments with valet parking and pool access, but no standalone day pass.

Seattle, Washington

A moderate-priced day spa in Bellevue's Wilburton area offering full-body massage and foot reflexology alongside a sauna, steam room and cold plunge.

Seattle, Washington

A two-tank float therapy and infrared sauna studio set inside a ranch house near Kent, Washington, open by appointment only.

Miami, Florida

Medical spa in Miami's Edgewater doing Botox, fillers and facials, plus a sauna, steam room and thermal pool for aftercare.

Vail, Colorado

Hotel spa inside Park Hyatt Beaver Creek with a 5-step hydrotherapy circuit, sauna, steam room and day-pass access to massages, facials and fitness classes.

New York City, New York

Luxury hotel spa inside the Lotte New York Palace on Madison Avenue, offering ila's organic treatments, sauna, steam room and private yoga studio.

The Hamptons, New York

A small day spa on Main Street in East Hampton offering HydraFacials, organic facials, laser treatments and massage, with a sauna and relaxation lounge.

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

Sedona, Arizona

A Sedona day spa focused on deep tissue massage, fascia work and facials, with a sauna, steam room and thermal pool on site.

New York City, New York

Medical spa in Mountainside, NJ offering body sculpting, Botox and IV drip treatments alongside a sauna, steam room and pool, by reservation only.

San Diego, California

Day spa in San Diego's Hillcrest neighborhood offering steam room, dry sauna and jacuzzi, open seven days with free parking nearby.

Lake Tahoe, California

Lakeside spa inside Tahoe Lakeshore Lodge in South Lake Tahoe, with a hot tub, polar plunge and dry sauna, by appointment only.

Santa Barbara, California

Downtown Santa Barbara medical spa combining massage, facials and infrared sauna with Botox, fillers, microneedling and IV therapy.

Tampa, Florida

Adult-focused day spa in North Tampa offering facials, massage, waxing, infrared sauna and salt therapy, open daily with walk-ins welcome.

Nashville, Tennessee

Upscale Midtown Nashville day spa with sauna, steam room and cold plunge, offering massages, facials, body treatments and couples packages.

Virginia Beach, Virginia

A day spa in Virginia Beach's North Central area built around scalp treatments, massage and facials, open daily from 9am to 10pm.

Seattle, Washington

Bellevue massage studio in the Crossroads area offering Swedish, deep tissue and couples massage plus sauna and steam room access, walk-ins welcome.