Have been during the two Easter weeks 13 times. If you have been before and it was not those two weeks, July 4th, or Christmas, just double (if you went other spring break weeks or summer) or tripple (if off-season) the crowds you saw before. At noon at MK, if you stand at the base of Main Street and look down toward the castle, you won't see the street, you won't see the sidewalks, all you will see is a mass of bobbing heads. The theory that maybe it won't be so bad because many schools have spring breaks during weeks other than those two Easter weeks is one that has never come true since WDW opened. Go early or use fastpass (which run out for popular rides for the whole day and night by noon) to avoid two hour lines (three at Test Track). Even low attractions like the Treehouse get over 1 hour lines. At MK, some rides open up during 4 to 8 p.m. as everyone heads to dinner (but the crowd gets huge again after 8). Likewise at Epcot and MGM, you can do a number of things fairly easily after 3 but not the real popular ones and sometimes at AK after 5. If you want to eat at a sit-down restaurant in a park for dinner, you must make a ressie in advance. True story: we once saw a family of four walk up to the CM at Crystal Palace at 5:30 on the Thursday before Easter and ask for "the next available time" and the CM, after perusing the computer for a while, said, "Tuesday at 8:30." Even counter service places get 45 minute lines during prime eating times. Hotel restaurants are often easier to get but you should still make a ressie in advance. Waterparks fill to capacity by 11 and then open up again after 2. If you want chairs at those you need to be there early in the morning because the morning group grabs and holds them. It is near impossible to get into first Fantasmic unless you get the dinner package or get in line 70 minutes or more before starting. However, they usually have two Fantasmics a night during the Easter season and the second one never fills so you can walk in at the last minute. Guests start grabbing the curbside and other good parade viewing places starting 2 hours before the MK afternoon parade. The nighttime parade usually shows twice and like Fantasmic you are much better off going to the late one.