I checked into the Park Hyatt Sydney where I’ve had mixed luck at best with upgrades.
I arrived early on my first stay there and was told that my pre-assigned room wasn’t ready — but that if I wanted to pay an extra AUD$100 per day I could have an Opera View room. This wasn’t even a larger room, just an upgraded view, and if it was available I should have been offered it as a complimentary upgrade as a Hyatt Diamond.