It won't happen when you stay on points, but it might happen if you are paying cash. We got our studio upgraded to a one bedroom when we were paying a member discount rate for one night in a studio before moving to a one bedroom. The only way it would happen staying on points would be if the room you were supposed to get was out of service for maintenance and they didn't have any other studios available.
DVC stays on points will usually never get upgraded, because they are point stays. Like Deb said, this sometimes happens with cash CRO ressies, but it would be VERY rare to be upgraded with a point ressie. The problem is that it wouldn't be fair to all those members who used 40 points for that Friday night stay if someone arbitrarily got it for 20 points with an upgrade.
Complementary upgrades really don't happen and they should not. Occasionally one will get an upgraded room because if lack of availability of a certain room type or when a problem occurs.
Yes, we used points to stay concierge at the Grand Floridian last Labor Day weekend and we were upgraded to a Honeymoon Suite. (They are very nice and are in a secluded hallway only accesible to guest with keys for that corridor)
We just did. Booked 2 standard view rooms on points for the DisneyLand Hotel for 2 nights (3/3/ & 3/4). We were upgraded to connecting pool view rooms. Didn't even ask - when we got to the DLH Front Desk for check in, the CM smiled, said "Welcome Home", and told us about the upgrade.
We had five nights on points at Contemporary Resort, plus the first and last days on cash. We couldn't get the same type of accomodation for the first night since nothing was available when we added that night. When we checked in, we asked if it might be possible for us to spend all seven nights in the same room. We were told that they were very careful not to change room types with DVC reservations and that we would have to move after the first night to our six nights with the same room type. Both room types were in the South Wing Building, one was a water view, one a garden view.
Upgraded to pool view rooms on both stays at DLH on points. (2001 and 2005) No upgrade at GC on points in 2001 - small room overlooking entry portico and parking lot.
I believe the original question was "at OKW", and I still doubt that would happen on a points stay unless (as Dean said) there was a problem that took a unit out of service, and even that would have to mean full occupancy.