I don't think that Easter Sunday itself is any more crowded than all the other days surrounding the holiday. Thank God, Easter still hasn't been hit by hyper-commercialism, and remains much more of a religious holiday in the US (as compared to Christmas that is).
But the day is exceptionally crowded. But that's because that whole time period is terribly crowded.
In other words, I wouldn't block off Easter Sunday as opposed to say the Saturday the day before (which i would think is even worse, since no one's in church on Saturday).