I am using a crowd estimator from
www.touringplans.com. If you are a Mousesavers member or own the Unofficial Guide to WDW by Sehlinger and Testa, you can get a discount on the $7.95 annual cost.
I bought it because I was trying to figure out the crowds, since the only time I can visit this year is during my niece's Spring Break. TP.com has a very well researched crowd estimator. For people who are visiting just prior to Easter, I agree with another poster, you may be seeing peak crowds and waits of 90 - 120 minutes.
I would say that if you are worried about the crowds like I am, it is worth the money to get some background on the probable crowds in relation to holidays and spring breaks, plus official and unofficial (Gay Days is an unofficial WDW gathering/event, and brings significant crowds, as an example) events.
They give a scale from 1-10, with 10 being the highest. I will be home from 29 March until 4 April, and it looks like my niece and I will be dealing with 7-9 levels the whole time. Since our dates aren't flexible we don't have any choice.
If you are like me and can't change your plans, you might want to look into the touring plans they offer on the site. A friend of mine used one with two of her four children and she said it made 20-30 minute differences in their wait times. To me, that is worth it.