Spas with hot tub

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.

Hotel spa inside Florence's Four Seasons, with a walled garden pool, whirlpool, sauna, steam room and couples suite, open to day-pass guests.

Adults-only resort spa built into a wine cave in Napa, with a vineyard-view pool, sauna, steam room and hot tub; reservations required.

A 38,000-square-foot resort spa at JW Marriott Desert Springs in Palm Desert offers day passes, saunas, a saltwater lap pool and couples suites.

Day spa in Sedona with eucalyptus steam rooms, saunas, jacuzzi and a fitness center, offering day passes and memberships for walk-in guests.

An RV resort and hotel in the desert near Anza-Borrego with outdoor pools and hot tubs open to day visitors, no treatments involved.

All-inclusive multi-night wellness retreat in Pisgah Forest, NC, combining fitness classes, spa treatments, guided hikes and farm-to-table meals in private

Hotel spa at the Catamaran Resort in Pacific Beach, San Diego, with a bay-view hot tub, pool and restaurant, open to hotel guests only.

Adults-only hotel spa inside La Concha Resort in Condado, San Juan, offering couples massages and a small treatment menu for guests 18 and up.

Adults-only resort spa in Napa Valley with pools, sauna, steam and a fitness center, open to hotel guests and club members via day pass.

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

A 25-room Sonoma hotel in Forestville with a spa barn offering sauna, steam and pools, mainly for overnight guests.

A hotel-guests-only desert resort in Desert Hot Springs built around natural mineral hot spring pools, with spa treatments and overnight stays.