Four Seasons Hotel Istanbul at the Bosphorus

Though it's been open for almost a decade, the Four Seasons' second Istanbul property (the original Four Seasons Istanbul occupies a former prison in the Old City) retains its position at the top of the market. This is thanks to impeccable service, impressive amenities—the award-winning 22,600-square-foot spa offers not only traditional treatments but Turkish baths in private facilities—and the always-buzzing YALI bar and lounge, where the city's social elite gather nightly over cocktails and Turkish-inspired bites. A private dock facilitates airport transfers by boat, as well as providing a direct connection to the sister property in Sultanahmet.