Fairmont Century Plaza

The reborn Century Plaza in Century City houses one of the biggest and best-equipped hotel spas in Los Angeles — two floors of it, with a Himalayan salt room, aromatherapy steam, and a sprawling hydrotherapy circuit of pools, fountains, and contrast experiences — the sauna itself currently lives inside the bookable sauna-and-ice-bath contrast sessions rather than the open facilities list. If your priority is range and space rather than boutique intimacy, this is the LA pick: there's genuinely a lot of heat-and-water to work through, and the facilities feel brand new because they essentially are. Rooms are sleek, modern, and generously sized, and Century City makes a convenient, low-fuss base. It's polished and contemporary rather than romantic, which suits a serious wellness session down to the ground. Sauna and the thermal circuit are generally included for guests; leave a couple of hours to do the whole hydrotherapy run justice.