Some say the week before is heavier, some the week after. Have done both many times and in reality they are about the same. Crowds start to build the weekend before Easter and then the worst are Tuesday before to Thursday after. MK is always the worst. AK is usually atrocious mainly because it does not take that many to pack that place to the gills. Epcot always seems somewhat OK. MGM seems to have the most variation from one day to the next -- between crowded and packed to the gills. Some points:
1. There are extended hours. How extended depends. Years ago MK went to 1, then for many years it was midnight almost the entire two week period. Lately (post 9/11), it has gone to 11 or midnight some nights but even down to 10 others. A similar trend exists at MGM -- in early 1990's it went to midnight, then for several years to 11 and since 9/11 it has been 9 or 10, and 11 only a couple nights. The same has happened to the MK nightly parade and Fantasmic. Pre-9/11, there was always two of each every night. Since then some nights have only one. That makes a huge difference for Fantasmic. When there is only one, you need to get there 60 to 90 minutes early just to get in; when there are two the second one never fills and you can walk in at the last minute to that one. Thus, getting the dinner/Fantasmic package is virtually a necessity when there is only one so you don't have to wait in line forever.
2. If you can, avoid MK on Easter Sunday. That is its worst day, sometimes reaching capacity. Many go there on Sunday under the belief that something special happens there that day that does not happen other days of the week. A completely false belief. There is nothing that happens at MK on Sunday that you cannot see other days of the week--example, the Easter Parade, which is just the daily parade at 3 with Easter themed floats added, plays the entire week leading up to Easter and on Easter. Epcot usually has its lightest day of the holiday season on Sunday, as does AK, and even MGM is not bad. Other than Easter Sunday, the day before Easter is also fairly good for all parks except MK. Note, that the day after Easter is often MK's 2d worst day of the holiday season. In any event, MK is just very crowded everyday so there is really no easy one for that park.
3. Popular rides can get sustained (all day, all night) lines of 90 minutes to 2 1/2 hours; Test Track has gone to sustained lines of over 3 hours (although most everything else in Epcot is open much of the day; the addition of the new space ride will likely mean Test Track decreases some, while that new one goes to 3 hour lines). Even Swiss Family Treehouse gets to an hour. Most crowded time of day for any of the parks is about 10:30 to 3. If you go early, you can often hit a few things before crowds arive. Use fast pass for popular rides although those can run out for the day before noon. There are sometimes windows of oppurtunity where even some popular rides will fall below 35 minutes -- at MK during parades and at MGM during Fantasmic (first one when there are two a night).
4. At different times of day certain rides may open up. For example, Pirates and Haunted Mansion can have morning to 3 p.m. lines of 60 to 90 minutes. Between 4 and 8 p.m. they can become virtual walk-ons. After 8, nightly crowd returns to MK and the park becomes overly packed again. Except for Test Track and likely the new space ride, Epcot is fairly good after 3; likewise MGM except for Rockin Rollercoaster and Tower of Terror; things at AK can lighten after 4.
5. Never walk into Epcot early and head straight for Spaceship Earth. Most do that causing it to have an hour and longer line in the morning. After 2, it is a walk-on. Likewise, never exit a large theater show (like Indiana Jones) and head for the next nearest attraction (Star Tours in relation to Jones); again most everybody does that, causing a huge line at that next attraction, when often it is easy to get on at other times in the afternoon or evening.
6. Check for actual hours when you get there. They do sometimes change usually to the longer during that time. They sometimes open all the parks early and not just the early entry park. Things like that are never announced in advance and often you get no more than a day's warning.
7. Waterparks, unless it is too cool (it is usually very warm that time of year) get hugely crowded and often reach capacity by 11:30. They lighten after 2.
8. If you want a sit-down dinner in a park, make your ressies well in advance. Walk-ups often are disappointed to be told not only that there is nothing avaialble for a long while, but there is nothing available period for that night or next one. Do the same for any character meals. Reservations for resort restaurants, and if desired for lunch in the parks, can otherwise often be had by just calling the day before or even morning of.
9. At that time of year, parade sitters actually start lining up for the MK daytime parade two hours before. We find it best just to find some elevated area shortly before the parade (like the Town Hall steps).
