The parking during Sundance is a straight up mess. You have to get to the resort early or you flat out won't be able to park. One day last year during Sundance, I got there at like 11, and drove around the parking lot for an hour, then tried to pay to park underground, which was full, then tried to go park anywhere else, and I think I ended up parking in one of those parking garages on mainstreet in down town PC, then walking to town lift.
I think they might have a shuttle where you can park at the high school that I didn't know about, but that's still way annoying.
Moral of the story, get there early during Sundance.