We went Easter 1996 (April) and loved it, like Sandie says its like a "good" Uk summer!!!! Warm and pleasant, not too much rain, but a bit cooler in the evenings. The plus is that the parks are open later with usually full fireworks and parades. To be perfectly honest, we didn't really find it unbearably busy, and we went to MK on Easter Day!! Then again we are quite relaxed about queues etc. probably best to get a 10 day or LOS pass so you can pop in and out of parks at will rather than having to be committed to whole days?