If it's the week leading to or following Easter, yes, it will be crowded. However, it is still managable.
1. Get to the parks at opening. You can get in a good 2 hours before the big crowds get there.
2. Make AR's for dining and make them soon!
3. Take advantage of morning EMH's. I would avoid evening EMH, they tend to be crowded and I am sure on Spring Break, they will be.
4. Make sure you have the ability to park hop. If one park is insanely crowded, you can always hop to another.
Have fun!