Osmosis, Sonoma County

For a totally unique experience, head to Osmosis for a Japanese cedar enzyme bath. In this fermentation bathing ritual, your entire body will be immersed in a blend of soft and fragrant ground cedar and rice bran with living enzymes. You'll sweat out all your toxins, and then follow it with a massage before lounging in a hammock in the lush zen gardens. It's the perfect retreat for a pair or even a small group. While they do offer group options, you can also create your own custom spa experience for up to 70 guests. // 209 Bohemian Hwy. (Freestone); reservations are available at osmosis.com.

Kabuki Springs and Spa, San Francisco

Kabuki bathhouse is known for its communal hot tub with cold plunge, steam room, and dry sauna with sea salt for a good DIY scrub. Chilled face cloths, flavored waters, and tea are also prepared and at the ready for a quick refresh. The spa has an extensive menu of of both eastern and western-style services; book a massage with a private bath ($180), a botanical peel facial ($190), or the Javanese lulur—a traditional Indonesian ritual with a massage, turmeric and rice body scrub, a moisturizing yogurt application, and exotic flower bath ($215). While the space is large enough to accommodate small groups, groups with six or more should inquire for a special reservation. // 1750 Geary Blvd. (Japantown), reservations (communal baths are $49/2.5 hours or $20 with treatment) are available at kabukisprings.com.

Healing Arts Center and Spa at Cavallo Point, Sausalito

In Sausalito, Cavallo Point's spa is a full-fledged wellness getaway with an array of traditional offerings—think massages, body treatments, water therapies, and facials—as well as such healing services as acupuncture, energy work, meditation, hypnotherapy, and guided imagery. There's even a heated meditation pool beneath the pine trees, eucalyptus-infused steam rooms, outdoor jacuzzis, a tea bar, and a shaman who can take you on a spiritual journey. Specialized treatments include the Mama Goddess Massage, focusing on the specific needs of expecting mothers, and a relaxing cranio-sacral massage. Shared activities include resort workshops, hiking, yoga, aromatherapy, and bocce. With so many things to do, it's easy to get lost here for an entire day. The entire spa is also available for buy-out. // 601 Murray Circle, Fort Baker (Sausalito), reservations are available at cavallopoint.com.

Pearl Spa, San Francisco

This Korean-style spa is ladies only, and it has some of the more unique offerings around, including a 24-karat-gold extract full-body scrub and massage, pool of marble-sized clay balls, and a Himalayan salt room. In addition to its range of services, Pearl Spa also has a jacuzzi, cold tub, sauna, steam room, and areas with plush chairs to simply relax. They take reservations for everything from birthdays to bridal showers, but expect to be in your birthday suit as no swimsuits or outside clothing are allowed. // 1654 Post St. (Japantown); reservations are required (services range from $90 to $200) are available at pearlspasf.com.

Piedmont Springs, Oakland

On Oakland's Piedmont Avenue, this quiet little sanctuary has four private outdoor hot tubs with jets (and cold water hoses if you want to cool it down), decking, and covered showers. At $30 per hour per person for a hot tub, it's one of the most affordable and efficient ways to score some R&R; plus you can comfortably fit four people in one. Those looking for a detox can also reserve the cedar-lined sauna or steam room ($20 for 30 minutes or $22 for 45 minutes), both with showers and separate dressing rooms, or make it a combo and get a tub and sauna in one ($45/hour). For extra pampering, peruse their selection of massages including Swedish, shiatsu, prenatal, and body treatments. // 3939 Piedmont Ave. (Oakland); reservations are available at piedmontsprings.com.

Archimedes Banya, San Francisco

Find a mélange of spa treatments from around the world with Greek, German, Russian, and Turkish hammam–style bathing. Soak, get a scrub, have a good sweat, enjoy a massage, and get a facial all in one place. There are heated rooms, a cold plunge pool, as well as signature offerings like the Russian-style venik platza, a massage-meets-light-beating with tree branches in a steam room. Afterwards enjoy the view from the deck with a bite from their international menu created with local and organic produce. The spa also books private events for groups starting at six guests ($75/three hours) and up to 40 guests in a larger group (inquire for larger group pricing). For those looking to go all out, the entire facility can be rented for 100 people. Each venue room offers seating, flat screen TVs, and a dining area. // 748 Innes Ave. (Bayview), reservations are available at banyasf.com.

Indian Springs, Calistoga

The grounds at Indian Springs are plenty large enough to accommodate a party, with mineral pools for adults only as well as families. The spa offers restorative options including massages, facials, and body treatments such as the 50-minute Wine Country sugar scrub ($205), halo therapy Himalayan salt room ($45/25 minutes), or their signature mud bath. Indian Springs mud bath ritual ($170), with pure volcanic ash and mineral water from their own geysers, is a must try; they've also got showers, full spectrum infrared saunas and textured walls in the mud rooms. The spa offers group retreats. // 1712 Lincoln Ave. (Calistoga); reservations are available at indianspringscalistoga.com.

LaBelle Day Spas and Salons, Palo Alto

Get your pals excited with a range of services, from facials to hair treatments to massages. Try the Brightening Lumipele Facial ($220), a highly advanced treatment aiming to reduce hyperpigmentation and even out your skin tone, or a special microchanneling and anteage package to stimulate collagen productions ($450). There are also special grooming services for men (including a back facial) and the salon's most trusted products are out for purchase. // 855 El Camino Real #95 (Palo Alto); reservations are available at labelledayspas.com.