Thanks for the information! We are really hoping for late May/early June. After looking at the calendar, I was thinking that we could go May 29 - June 3/4. Have you been during these times? How is the crowd, heat, rain? The last time that we went was in Feb. 2004 and the crowds were not bad at all! Our full day was Valentine's Day and we had such a wonderful time! It did rain but we came prepared with our ponchos!
Late April/Early May is noticeably better than late May/early June mainly because you won't have the Easter crowds, spring break is pretty much done with, and the kiddies are still in school. On the other hand, late May/early June allows you to see Star Wars Weekends which I would LOVE to see!!! After looking at the Unofficial Guides crowd calendar you will definitely be dealing with more people at the end of May as opposed to the middle of February. Although there is a saving grace if you do go at the end of May! His name is TourGuideMiKE and he tells you which days to go to which park. He rates his days using a green, yellow, red system and it really works! We coupled MiKE's green, yellow, red suggestions with the Unofficial Guides touring plans on our past trip and we didn't have to wait more than 15 or 20 minutes for any ride!
IMO, the main difference between early May and late May is that if you're trying to beat the crowds you need to have a stricter schedule for late May. Early May your schedule can be a bit more flexible. My biggest advice is to always question why people are doing what they're doing while in the parks.
DO NOT FOLLOW THE HERD!!! Pirates of the Carribean is a perfect example because you can either go right or left at the entrance. If you see a herd of people going one way, think about your options, evaluate the situation and if it seems feasible, go the other way. I've heard theories about only using the left line and sometimes this works but other times it doesn't. It all really comes down to thinking on your own and evaluating the situation at hand.
Another great way to beat the crowds is to get to the park 1/2 an hour (or earlier!) before they open and eat lunch around 11. You can also get into MK super early if you have a breakfast reservation for the Crystal Palace or Cinderella's Royal Table before the park opens. Acutally...you can likely get in even if you don't have a reservation! We had a ressie at CP but they didn't even look for our name on a list at the front gates.
Hope this helps! Sorry for the length!