-New Years Eve & Day
-Presidents Day Weekend, because it's a 3 day weekend often falling during the Daytona 500 which causes high crowds too.
-4th of July Week
-Mid June through Mid August because schools are out
-Mid March through Easter, due to Spring Break. I am there every year in mid-March the same time that the majority of Canada has Spring Break and it's worse than summer!
-Memorial Day Weekend
These times are all possible because people are off work and kids are out of school. The best times to visit are when school is in session, and there is no holiday in sight. Fall is ideal, from September through early November. The first week of December is also uncrowded, and all the decorations are up so it's a great time to go!
Thanksgiving weekend (busiest days of the year)
Christmas Eve / Christmas Day (second busiest)
Memorial Day weekend
4th of July weekend, especially if the 4th is on the weekend
Pretty much any major holiday where people travel and have time off.