Hyatt Regency Atlanta

The atrium here was John Portman's original experiment in the form: a cavernous open void with a skylight ceiling and glass elevators gliding up the walls, and it still stops people mid-stride. This conference-scale hotel spreads across three towers, from standard king rooms to the Radius, a glass cylinder with compact quarters and mosaic-tile showers that feel like a set from a 1970s sci-fi film. Polaris, the revolving rooftop restaurant under a blue dome, completes the retro-futurist mood.