We got sprinkled with Pixie Dust big time when we went for my cousin's wedding in Nov. I was the MOH and had booked a deluxe concierge room at Grand Floridian for the bride, myself, and the other 2 BM's the night before the wedding. We thought it would be fun to do a girls night in a cool room the night before.
When my cousin (the bride) and I got the GF to check in, we were greeted by the concierge and brought us up the checkin lounge. She was asking all sorts of questions, including why we were visiting, etc. As of course we told her that she (my cousin) was getting married at the Wedding Pavilion the next day. She started smiling and congratulating her and stuff and told us that we had a wonderful room booked.
A few minutes later we were heading down the hall with her to our room and she stopped in from of the Walt Disney Suite (yep, aka the Presidential Suite) and said 'this is it'. We thought it was a joke! But nope, she had us put our room key in and it let us in! Yay!!!

It truly was our dream come true! Ever since we were little the two of us had dreamt of staying in this room, and there we were!
It was an awesome and totally unexpected dusting of Disney Magic!
As a sidenote: We did not ask for an upgrade, and as others have said before, the best way to get one appears to just let it happen. Some had also posted that if you ask, that per Disney policy the CM is required to charge you for the upgrade if one is available and you are given it.