Virgin Holidays - As usual, they are late with info, just always rubbish!! lol
I think you come back just before the mad part the Thursday (24th) through Sunday (our first 4 days!) will be busiest.. Remember that the guys in the US don't get so much annual leave, so they seem to use the public holidays more than taking time off work. I don't believe the Touring Plans calendars anymore, they are always wrong now!
Year to date, the whole of Orlando has been quieter than usual, so I reckon it't wont be as bad as it has been previous years.