Spas with reservation required

Elkridge, Maryland

A halotherapy day spa in West Elkridge, near Baltimore, built around a salt cave, massage rooms and a yoga studio, aimed at solo adult visitors.

Palm Springs, California

Downtown Palm Springs day spa built around a natural hot mineral spring, with private mineral baths, sauna, steam room and massage.

Sonoma, California

Hotel spa at The Lodge at Sonoma with an outdoor terrace, soaking pool, plunge pool and barrel sauna, open daily 9am-5pm, adults-only, reservation required.

Napa Valley, California

A single-treatment float spa in Napa offering sensory-deprivation float pods with Epsom salt water, plus dedicated parking and walk-in access.

Springboro, Ohio

A wellness center in Springboro, Ohio built around a natural salt cave, with energy healing, sound baths and metaphysical classes for individuals or groups.

Los Angeles, California

Day spa in a Montebello strip mall plaza offering facials, massages and body treatments, open daily with walk-ins accepted.

New York City, New York

A no-frills medical spa in Manhattan built around lymphatic drainage therapy and acupuncture, open daily 10am to 9:30pm.

Carmel, Indiana

A no-frills contrast therapy studio in Carmel, Indiana, built around a 30-minute sauna-and-cold-plunge circuit for solo visitors.

Dallas, Texas

A no-frills massage studio in North Dallas offering Swedish, deep tissue and its own signature treatment, plus in-home and office visits by appointment.

Chicago, Illinois

A medical spa in Chicago's Lincoln Park offering Botox, dermal fillers, laser hair removal, IPL and semaglutide weight-loss treatment, priced in the moderate

Milwaukee, Wisconsin

East Town Spa in Milwaukee's Juneau Town combines a full-service salon and med spa with a thermal circuit of sauna, steam, pools and cold plunge.

Las Vegas, Nevada

A no-frills massage and facial day spa on West Flamingo Road in Las Vegas, open daily 10am to 8pm with walk-in and reservation options.

Ubud, Bali

An adults-only wellness retreat on Ubud's Ayung River offering multi-day healing programmes, thermal circuits and plant-based cuisine by reservation only.

Nashville, Tennessee

Float Horizen is a day spa in Nashville's East End offering sensory-deprivation float tanks, infrared sauna, massage and sound meditation sessions.

Tucson, Arizona

Day spa in Tucson's La Encantada shopping center with a thermal circuit of sauna, steam room, cold plunge and soaking pools.

Colorado Springs, Colorado

An adults-only medical day spa in Colorado Springs offering constitutional hydrotherapy, infrared sauna and homeopathy by appointment.

Scottsdale, Arizona

Hammam-inspired hotel spa at Omni Scottsdale Resort & Spa at Montelucia in Paradise Valley, with private suites and massage, facial and body treatments for

Sonoma, California

A moderate-priced day spa a block off Sonoma Plaza offering massage and facials from a certified therapist and licensed esthetician, with private treatment

Honolulu, Hawaii

A Thai massage day spa in Honolulu's McCully-Moiliili area offering solo and couples treatments daily from 9am to 11pm.

San Diego, California

A Clairemont wellness studio in San Diego pairing acupuncture and bodywork with an infrared sauna and a Himalayan salt room for classes.

New York City, New York

Adults-only day spa in Maplewood, NJ, offering deep tissue massage, bodywork and facials by appointment, open daily 9am-8pm.

Scottsdale, Arizona

Medical spa in South Scottsdale offering skin and wellness treatments, led by a board-certified plastic surgeon, open weekdays and Saturday mornings.

Richmond, Virginia

Day spa in Richmond's West End with massage, organic facials, HydraFacial, infrared sauna and herbal bath soaks; walk-ins welcome, reservations recommended.

Napa Valley, California

Adults-only day spa in Napa offering facials, massage, waxing and makeup services by appointment, open daily 9am to 7pm.