We flew in on Presidents Day this year and went to the parks for 4 days. I would say that it was on the busy side but they had extended hours which allowed us mid afternoon breaks and gave us plenty of time to do and see everything.
The weather was great. It was shorts and t-shirt weather for us. The kids even hit the pool during the day. Some people would say the weather was on the cool side but coming from the Pacific NW it was very nice.