An intimate subterranean getaway—only four treatment rooms and a petite mani-pedi area—in the city’s most ex­­clusive hotel, the Yabu Pushelberg–designed space is a marbled oasis of cool. Jazzy old French songs fill the corridor as you pad between treatment rooms, dip into in the mosaic-tiled pool, or hop on a spinning bike in the mini-gym. Jetsetters will en­joy the Éclat Contour for Jet-Lag ($200), a 90-minute treatment with Yonka products that combines a facial targeting under-eye circles, followed by a leg massage to ease stiff intercontinental gams. Peckish after pampering? Order from the hotel’s Mark McEwan–directed restaurant, One.