Sure, you can go by day, but the ultimate way to experience this Japanese-style spa in the hills above town is at night, when the steam rises off the outdoor soaking tubs and dissolves into the stars overhead. This is hands-down one of my favorite places in the city, from the kimono you get at check-in to the pine-scented lotion that lingers long after your soak. Choose from private or co-ed communal tubs—there's a separate one just for women—which have access to saunas and, if you're feeling brave, chilly plunge pools for a (supposedly) healthy shock to the system. Massages and other body treatments are extra, and two "spa suites" have private changing rooms and showers. You can spend the night in one of 13 rooms, and with the addition of Izanami, an on-site restaurant serving Japanese small plates, you may never have to leave.