One of the first times we went to DL I brought one of our SLRs. I grabbed a number of good shots, but it's a big bag to lug around for 12 hours a day. And, of course, I was paranoid it would get wet on our favourite rides (so we ended up stashing it a lot).
Recently, we've taken a Powershot and our smartphones. We got lots of good pictures, but not as many great ones, so I think it's a tradeoff.
For our next trip I'm seriously considering picking up a micro 4/3rds with a 27mm lens (techno mumbojumbo meaning: it's thin, and it takes great people shots). These 4/3rds cameras fit in your jeans pocket, and they have much bigger sensors (and better electronics) than most compact cameras like the Powershots. These cameras take amazing pictures at half the size.
I'm hoping one of these semi-pro cameras and a few ziplock bags will make for fun shots on Splash Mountain and The Grizzly River Run.