The characters at the Dance Party tend to be a lot easier to get a picture with than at other small entertainment offerings such as the Hoedown. If there are too many kids, then you may be out of luck, but generally speaking we have always found that the characters are more than willing to pose - albeit briefly - for a photo.
This version of the Dance Party is very similar to the one featured in the day time, except it has a more "festive" feel for the party. Also, Goofy is likely to make an appearance (he doesn't during the day) in his special space outfit, as well as Stitch appearing in his 626 costume!