This enormous, 72-story convention hotel is located in the heart of downtown Detroit in the Renaissance Center, known locally as the "Ren Cen." While public and private efforts have been made to add something..anything...to the Motor City's hub, it is still a vibe-less concrete morass. Marriott's 1,298 colorful rooms' contemporary furnishings and floor to ceiling windows with city or river views are comfortable. This Marriott tries to manage solid service notwithstanding its huge size. It's getting there.
The 40th floor on-site workout room contains machines in good condition. Dumbbells in the room are the adjustable multi-weight variation (the square-ish, one-piece dumbbell that can be added to or subtracted from to vary the weight) which can prove cumbersome, especially when your routine calls for multiple weights. We suggest you look to the Hoist stack-loaded machines for any strength work.
Swimmers, and those wanting a more elaborate workout alternative should consider the Boll Family YMCA ($20/day). The YMCA is less than 10 minutes from the Marriott.