JW Marriott Chicago

The honest one. Most hotel spas make you guess what access costs; the JW Marriott posts it — fifteen dollars an hour for the steam and sauna, no treatment required. That transparency alone earns it a place on this list, but the facilities close the case: this is one of the only true infrared saunas in a Chicago hotel, sitting alongside a steam room and two hammam chambers in the spa beneath Daniel Burnham's landmark Continental & Commercial Bank building in the Loop. The infrared runs gentler than a Finnish box — longer sessions, deeper soak — and pairs well with the hammam's wet heat. Rooms upstairs are big and business-solid. If you work downtown and want a real sweat without a spa-day production, this is the move.