Hotels don’t get much sleeker than Hoshinoya Tokyo, a spectacularly modern take on a ryokan (traditional Japanese inn) that’s ensconced in the city’s thrumming financial district. You slip off your shoes when you get there and you’re in another world-a calm, seductive, luxurious one-as you make your way down the sandalwood-scented, tatami-lined hallway. There’s a sake-stocked lounge that’s definitely worth a linger, but the onsen is the biggest draw, with its series of indoor and outdoor hot spring bathing pools on the seventeen-story monolith’s top floor. The naturally salty water is therapeutic, energizing, head-clearing. You haven’t really experienced Tokyo until you’ve gazed out at its twinkling lights from a bubbling tub of hot spring water.