I stayed with family at the Marriott's MountainSide on June 18, and again on the 23rd. Both times the rooms were gorgeous, immaculate, and comfortable (even the sofa-bed, which I used, was very comfortable...). The first time was a two-room suite, with virtually a full kitchen.
If I were pressed under duress by a terrorist organization (or the NSA) to find a fault, it would be the current construction had the parking lots all screwed up - and after driving all day, following "detour" signs while your GPS frantically tells you "you missed your turn you imbecile!" is... well... it could have been better.
However, the check-in staff were very good about offering the shuttle bus and a baggage porter to help from the lower underground lot up to the hotel.... absolutely no complaint there (I chose to walk both times.. after 10 hours in the car, you need a stretch!).
This hotel IS out of my usual price range, but given the opportunity again, I may just splurge for this place if I find myself in Park City Utah again.