We were there Easter Week last year. I second everything posted by Babs50. Get to the park early and use fastpass. The only park that we found truly unbearable at times was MK. It would get hard to even walk around after noon. But, MK opened to resort guests at 7am, so we'd have 5 hours at the park before noon. Then we got out of there and went back to the hotel to swim and relax, or we went to Epcot. Epcot never seemed to crowded. The lines for MS and TT would get very long, though.
My other tip would be to make ADRs if you want to eat in a sit down restaurant. We were so glad we made more ADRs than usual. If was nice to sit down and relax. And we saw many people trying to eat ANYWHERE and discovering most of the restaurants were booked. We spent more on dining than we'd hoped, but it was worth it.
There are 2 places it worked going later in the day. We went to Blizzard Beach at 2 pm, which seemed to be the time everyone was starting to head home. They were open til 6 so we had 4 hours of fun. We'd already had lunch, so we didn't have to worry about a meal. By 5 pm we had the place to ourselves. We also went to AK at 3:30. After the 4 pm parade, everyone went home and the park was very uncrowded for the next few hours.
We had a great time. Don't let the crowds worry you. The parks are open so early and so late that you'll get to what you want to do. We just didn't get much sleep!!!