Probably the best Marriott property I've seen in the United States (and I have stayed in many).
Modern, clean, bright, new, with many interesting touches and thought out design elements.
We got a corner room (with 2 bathrooms) that was very spacious. The floor-to-ceiling windows along the bedroom and a hallway of our room added to the airy, open feeling. Room was very technologically advanced -- chargers, speakers, 2 huge flat screen TVs, accent lights, dimmers on every switch, lights build into sink faucets, rain shower, 3rd TV behind the bathroom mirrors, curtains electronically controlled... I could go on and on. In a time when more and more places seem to cut corners for savings, this place does not.
Concierge was also helpful and offered later checkout so that I would not have to rush my spa appointment. Also very nice concierge lounge. Gym facility(shared with JW) is super clean, with floor to ceiling windows and excellent equipment. I tried 5 properties on this trip to Miami, and Art Beaux was by far the best.