We went for those same dates in '02. I hate to be a bummer, but the weather was so awful that I am planning another trip a different time of year so we can enjoy the parks more.
Our problem was that it was extremely rainy. Now I know, you have to go with the flow and not let a little water ruin your fun. But no matter how optimistic you are about it, the parks lose their atmosphere which is almost what I love best. All the sidewalk venders and performers are gone when its pouring and the guests start running for cover (even with rain ponchos on), our shoes got completely drenched, and it rained every single day and from what I understand, this is pretty common .... anyway, I could go on and on about the rain, but for the few hours that the sun came out, it was soooo hot and sooooo humid that we couldn't decide what was worse.
As far as the crowds go, we just followed all the advice we gained through this board and it wasn't a problem.
Go mentally prepared to deal with the weather the best you can! Definately bring 99 cent rain ponchos from home, and stuff newspapers in your shoes to dry out overnight. Oh yes, and don't forget the sunscreen and mister's for the other half of the day!