I went last Thanksgiving and didn't find it to be terrible. We actually left Thanksgiving afternoon however so I can't speak for the days following. When we arrived that Saturday the parks were very manageable. We didn't do the Magic Kingdom the day Space Mountain officially opened, but a friend did and said that park was packed. The weather was perfect, though we did have one rain day, it was warm enough to swim and wear shorts (we are from the south so think 70's) though Central FL weather can hit the extremes that time of year. I would go for Thanksgiving again with no problem.