Courtesy Four Seasons

Even though it opened back in the spa Middle Ages (1999), the spa here anticipated the treatment-suites trend. Eight years on, the seven lavish spaces still dazzle. Most are about 800 square feet, the penthouse is nearly 2,000, and they have fireplaces, outdoor soaking tubs, and daybeds so big I felt like Gulliver on the island of Brobdingnag lounging on one. They're as gorgeous as the nearby Lanna temples that they reference: gold-leaf Bo trees painted on the maroon walls, purple Thai silk on the massage beds, and frescoes of villagers at play. Treatments are luxe and local, too. Body treatments and facials use Ytsara, a good organic-leaning Thai line, and Thai massage with Jirasak goes down as one of my all-time best. — A.A.

800-332-3442, www.fourseasons.com