In 1999, we arrived the Saturday before Thanksgiving and left the Saturday after. We prepped big time for crowds - We were the 1st ones at the MK gate in the morning. I had mini maps and tour routes from the Unofficial Guide. Two months prior to our trip I had the kids practice wind sprints with full backpacks every morning and night (ok I'm kidding - but only a little bit)
But...
From the Saturday we arrived till Thanksgiving day, we practically owned the park. I have a picture of my daughters lying down on Main Street reading their park map with noone else in view. From that point, we ditched the preplanned route and went where we wanted. On Thanksgiving day, (as we enjoyed our turkey leg - or is it ostrich leg - in the Animal Kingdom) the parks filled up and stayed that way till we left. I'd go again that week in a heartbeat.
This year, (our kids first return trip and our - my wife and I - fourth trip), we are arriving 4th of July week. Needless to say the wind sprints with full packs are back in gear, my son taking Fastpass practice at the ATM, and my youngest is hanging from the bannister every day in order to meet the Rock n' Roller Coaster height requirement. Wish us luck and the same to you.
rl