We always used to go Memorial Day week. Here's what my experience was. The Friday, Saturday and Sunday BEFORE Memorial Day Monday are super crowded. Memorial Day Monday itself is super crowded. The Tuesday after it's a little better and stays that way until the next weekend, when it gets super busy again. But all in all, it's a pretty busy week. It's also very hot, humid and rainy - but good anyway because the parks generally had longer hours and all the parades/shows were running. We liked going then.