La Prairie Spa at Hotel Bel-Air
Los Angeles, California (hotelbelair.com)
Why it rules: This Spanish-mission-style hotel — nestled in the rustic canyons of L.A. — recently reopened with a whopping $100 million, two-year renovation and a brand-new spa that marries intricate design (think hand-painted murals and a chic black-Swarovski-crystal reception desk) with serene garden-side treatment rooms. The specialty of the house? High-tech Swiss skincare coveted by the likes of Emily Blunt and Zoe Saldana.