Completed a 2 night stay at the Cosmopolitan mid-week right before NYE.
It was booked through Marriott with the Amex bonvoy brilliant. got the $300 bonvoy statement credit within a few days of booking.
They recognized the gold elite status at the invited guest desk and offered me a 52nd floor fountain view 1br Terrace after asking for available upgrades.
They also informed me of the Autograph lounge access and was able to grab coffee throughout the stay which was nice.
We mostly dined within the hotel due to late reservations and was able to get 6x back on everything using the brilliant.
Overall a very pleasant stay. I'll have to come back once more before it goes full-MGM.