Easter weeks (before and after) are the second busiest time at the parks. This past Easter was incredible -- Fastpasses were sold out by Noon, waits were 130-minutes at Test Track. It is very, very, crowded. However, we go every year at this time because of my son's school schedule, but with careful planning you should be all right.
Go early to the parks, leave by Noon to go back to your room, and return to the parks after dinner. One good thing -- the MK is usually open quite late, and there are always two showing of Fantasmic at MGM and two Spectro parades each night.
This past Easter, they closed the MK to outside guests for a couple hours each day because of crowds. It was definitely the worst Easter in the 9-years we have been going. If there is any other time of year that you can go (other than Xmas) I would consider going another time. Try and stay away from MK on Easter Sunday -- very crowded!!!