We visited WDW last Easter DW-?, DS-10, DD-9, DS-5 and DD and we found that the best thing was to hit whichever park you're going to early. Most of the parks started to become more crowded around noon.
Our first day we visited MK and headed directly to SWF for a fastpass then on to BTM and back to SWF. You can usually ride BTM 2-3 times before you FP time at SWF. Then we jumped over to HM. Before entering HM I went ahead and got our FP for Peter Pan. After PP I usually run ahead and get our FP for WTP, this ride usually sells out of FP very early. While waiting for WTP you can hit IASW, Carousel, Snow White and probably lunch or even the Castle Forecourt show.
Same thing at MGM, we headed first thing to TOT and RNRRC and spent the rest of our time on the other rides getting fast passes when needed.
At AK we usually can finish it by 1-2 pm. We try to hit the Dinosaur area first then head to Asia for the water ride and then over to Africa. This has worked great fro us the past 2 years.
A couple of inbetween days were spent at the Water parks for rest.....then back to the parks.
We've found it best to hit the major rides as soon as possible before the crowds start to build. This gives you more time to enjoy some of the other rides while everyone else waits in line for Big ones.
Have a great time, we'll probably be visiting WDW again this Spring break April 10-20 and can't wait.