10% discount on the UMP (unlimited magic pass) aka LOS (length of stay).
They used to have another type of pass for
DVC'ers, but it was confusing, and frankly there was no real advantage to it; last I heard they discontinued it because of lack of interest.
If you plan on 10 or more days at the parks in a year, the annual pass is frequently your best bet. A lot of people plan trips such that they can take 2 trips within the year time frame of the annual pass.