I've been twice in April during Spring Break for NY state public schools. Both times, the weather was absolutely gorgeous, upper 70's and low humidity, with no rain that I recall. The first time, way back in 1993, it seemed horribly crowded - however, I did no advance planning and that was part of it - the shock of seeing such crowds and having no strategy for working around them. Last year's trip was wonderful, though. Crowds were quite manageable. I saw only one ride with a long wait (Test Track) and had a very relaxed vacation. Even the resort (ASMu) was pretty uncrowded - the worst thing was the older Spring Breakers cavorting in the "quiet" piano pool until 2 am. In fact, I enjoyed myself so much I'm going back this year!