We're planning a trip to Disney World over the 2011 Christmas break. I think we'll arrive mid-day on Sunday 12/18 and leave mid-day on Friday 12/30. We'd like to go to the Universal parks for a day or two during that time. We have Disney down to a science, so I'm not worried about finding good days to visit the WDW parks. However, I'm not nearly as familiar with Universal as we've only been to each park once (and that was before Harry Potter). If we're looking to go to Universal at the least busy times during that very busy period, which days do you think are our best bet?