Spas with private suites

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.

Nashville, Tennessee

A Finnish-inspired bathhouse and salon in a converted East Nashville factory, with sauna, steam room, cold plunge and private suites for couples.

Aix-les-Bains, Auvergne-Rhône-Alpes

An upscale day spa inside Hotel Le Riviera in Aix-les-Bains, with pools, saunas, a hammam and eight treatment rooms open to walk-ins.

Calistoga, California

Hotel spa in downtown Healdsburg with a garden patio, jacuzzi and pool access, open daily 9am-5pm for guests and day visitors.

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.