As I mentioned a couple weeks ago, I used the Park Place airport checkin in December when I arrived at 9 am..Only 1 agent but no line..he was happy to check me in then but was limited to those rooms that were clean & ready to go at that moment so no upgrade for the Flamingo (not sure if he would have upgraded me later in the day or not). So I got just a regular room on the 15th floor, which was OK.
But it sure was easy to check-in at the airport. Nice to be able to go right to the room later and not have to stand in line at the hotel..