We've had a few upgrades! Some were random, some were due to mishaps, some I think were due to some clever planning.
In recent memory:
FEB 2016 CBR booked standard queen, upgraded to King water view on our 1 year wedding anniversary trip when we asked if there were any King rooms available at check in. We were curious about the cost to upgrade, but a super nice cast member just gave it to us!
FEB 2020 CSR booked standard queen, had requested cabanas area. When we checked in (at desk) they said they could give us a room in cabanas, but they suggested with a wink we keep the room that had been assigned to us. When we opened the door it was a one bedroom suite in casitas! This was our first ever experience in any Disney suite! It was soooo exciting!
AUG 2021 YC trip that didn't go as planned. Luck of the draw we probably got the worst room in the hotel. When we got there the porter told us we had been upgraded to club level! We were excited, until we realized club level wasn't open lol- and our room view was the service exit where the dumpsters were and CMs took smoke breaks.-also super far from anything. We didn't complain though, because somebody has to get that room, and we weren't going to be spending much time at the room that trip anyway. My toddler son ended up having a medical emergency and was taken by ambulance from YC in the middle of the night. The way YC handled it was super disappointing. Not to mention they refused to take out the dirty diaper filled trash even every other day. Ended up being the worst Disney trip we have had in 30 plus years. I was super upset with the lack of care that was given in regards to my son's medical emergency, so I did write a letter. A few months later Disney called and gifted us two nights at any resort of our choice. We chose GF, because it had been out of reach because of cost in the past.
FEB 2022 Comped GF Lagoon View nights. We decided to extend our trip by three nights, at our cost. This is where I think I was a little clever. I booked CR garden wing room, suspecting that it was going to be under renovations by our trip. I was right, and they upgraded us to the GF and let us stay at the Lagoon View level for the remainder of the trip. So CR GW to GF LV. So anyway, we get to the GF room and my mother and I go to get massages at the spa (but beforehand we stop by the front desk to speak to them about a delivery that was supposed to be in our room that was not- a big balloon bouquet for my father who had just retired) while we were discussing, the balloons were dropped off, and we didn't get to get pictures of dad receiving it- basically the timing was just off. The front desk manager was so nice about it and ended up upgrading us to a TPV in an extra large "standard" room with a sitting area and two balconies. Watching the fireworks from our GF room balcony was an amazing experience, one I never thought we would have.
NOV/DEC 2022 Not a Disney upgrade/pixie dust- but made a new friend on Disboards last year who has become like family and has some major pixie dust power! Will be staying at a GF CL outer building 2 BR and then moving to GF Standard on a pretty much unheard about deal. So I wasn't upgraded by Disney but a friend got me an AMAZING deal that would be out of reach otherwise that pretty much feels like the biggest upgrade I could imagine.