Newer, fancier establishments may have eclipsed Calistoga's oldest spa, but loyal fans appreciate its reasonable prices and unpretentious vibe. The mud baths here are a mix of volcanic ash and Canadian peat, warmed by the spa's own hot springs. Fun fact: back in 1952, "The Works"—a mud bath, steam room, blanket wrap, and a massage—cost $3.50. The charge now is $139. You can also get a facial here.