I find that if I'm going to get upgraded it usually happens before check-in anyhow. So if I pull up my reservation (IHG, Hilton, Marriott, etc.) and see that I've already scored my desired/expected upgrade - I check in with the app so I get the room I want. If I haven't been upgraded or it's some bogus upgrade (oooohhh a higher floor) than I usually wait until I get to the desk.