Honestly, even with Kimpton Inner Circle status the Onyx is the least interesting of the three Boston properties. The "upgrades" to the top floor are the same size rooms as the non-upgrades, and they have their HVAC systems for the hotel right on top of the rooms and if you're sensitive to mechanical noises it's best just to be on a regular floor. The gym is tiny (but they have an agreement with a local gym a couple blocks away so you can work out there) and the location isn't the most ideal unless you need to be near the north train station for some reason. If pricing isn't much different, the Nine Zero is much better value for the dollar.