I went up March 29-31 with the wife. IOA was packed that Saturday afternoon with wait times for the thrill rides at 1 hour.
Daughter went up next week with school and it was packed. And the thing is, when kids go with a school trip, they have no way to get an express pass, and they usually get there around 10am with the rest of the crowd. She only got on a few rides, and then walked around with her friends.
I'd have to say the crowds are back for the summer. The trick is to be there early at 08:30am. That will give you a lap of walkon rides. By 11am, everyone is there, but you will have done the major rides if you time it right.