Spas with moderate

Palm Springs, California

Hotel spa at the Grand Hyatt in Indian Wells with sauna, steam room, cold plunge and five treatment options for solo guests or couples.

Sonoma, California

A small hotel spa inside Cottage Inn and Spa in downtown Sonoma, offering seven massage and body treatments with a relaxation lounge and couples option.

Tucson, Arizona

A resort spa in Tucson's Starr Pass area with a saline lap pool, sauna and fitness center, plus signature treatments from $159 for hotel guests.

Krynica-Zdrój, Lesser Poland

Mountain resort spa in Krynica-Zdrój with indoor and outdoor pools, a sauna complex, and a clothing-optional 18+ zone; day passes available.

Berlin

A hotel spa inside The Mandala Hotel in Mitte, Berlin, with sauna and fitness areas, day passes for adults 14 and up.

Tucson, Arizona

Adults-only hotel spa at El Conquistador Tucson with a salt therapy lounge, heated outdoor pool and mountain views, day passes available to hotel guests.

Denver, Colorado

A 6,000-square-foot hotel spa in downtown Denver's Granite Tower, open to day-pass visitors 18 and older for $40 to $75.

Galway, Connacht

Adults-only hotel spa in Galway with a thermal suite, hydro pool and sauna; day pass runs about €50 and reservations are required.

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.

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.

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.

Miami, Florida

A hotel spa in downtown Miami with a day pass covering sauna, steam, cold plunge and thermal pools, plus 13 treatments on the menu.

Las Vegas, Nevada

A hotel spa at the Flamingo Las Vegas open daily 8am to 5pm, available only to hotel guests for treatments and fitness facilities.

Nashville, Tennessee

A hotel wellness area at Sheraton Music City near Nashville airport, open to guests 21 and up, with sauna, steam room, pools and a whirlpool.

Las Vegas, Nevada

Adults-only hotel spa inside Harrah's Las Vegas with steam room, sauna, hot tub and fitness center, open daily with set hours for guests.

Scottsdale, Arizona

A resort spa in Scottsdale's Arcadia area offering massages, facials, and body treatments, open to hotel guests and day-pass visitors alike.

Johnson City, New York

A 21-and-over hotel in Johnson City, NY, with a sauna, hot tub and fitness center for guests staying at the property.

Key West, Florida

Hotel spa at Southernmost Beach Resort in Key West offering massages and facials for guests 18 and up, with daily treatment specials.

Tulsa, Oklahoma

A hotel-guest-only wellness space at Brut Hotel in Tulsa, with a relaxation lounge, yoga sessions and an on-site restaurant.

Denver, Colorado

Adults-only hotel spa inside Gaylord Rockies Resort in Aurora, Colorado, open exclusively to resort guests with moderate day-pass pricing.

Houston, Texas

A hotel spa inside Hilton Americas-Houston in the Central Business District, open to hotel guests.

Tampa, Florida

A moderately priced hotel spa inside Le Meridien Tampa, The Courthouse, open to hotel guests and day-pass visitors, geared toward adults and couples.