I used eCheckin for my stay at Hilton Charlotte Center City this week. The hotel is sold out (not even diamond guarantee) and I was only able to book a 2 doubles room, so I figured I would use eCheck in to get a higher floor room. I was very surprised to see this morning in the app after I checked-in that I was upgraded to a city view corner room with a king which I prefer. This was the first time I've been upgraded after using eCheckin. This is a very nice change of pace from previous experiences!