We (party of 10) just went this past Easter. It was surprisingly crowded--thought that people would still be staying home due to 9/11 and terrorist bombings in Israel. All I can say about our stay in Florida--Lot's of Brits! Seemed like every other person was from the UK.
MK "sold out" several nights, meaning only those fortunate to be in the park by mid-afternoon (and I think resort guests) got access. So prepare to commit yourselves to fighting mobs of tourists.
We devised a strategy that got us through the masses rather nicely. It was the "Always Have A Fast Pass" rule. At minimum we'd grab our next Fast Pass when our current one was just beginning. At maximum, we'd grab our next Fast Pass when two hours had expired (had to do this once when our Splash Mountain FP return time was 4 hours later, but it got us on Jungle Cruise in the interim).
Over the course of a day, we'd end up doing something like 7 Fast Passes at MK, but we'd skip long lines at Splash Mountain, BTM, Winnie The Pooh, Buzz Lightyear, ect., and probably earned ourselves another 3-4 hours of riding time this way.
Of course, we wanted to ride/see everything, so hanging out in Fantasyland or Tomorrowland riding Tea Cups, the TTA, or seeing Timekeeper to wait out our return time for Buzz Lightyear wasn't a problem.
We used similar stategy for AK and MGM. Only had to really use FP for TT and Living W/ the Land at Epcot--no big crowds--but that should change by next Easter if Mission:Space opens by then.
Longest wait we had for the entire week-long trip was 40 minutes for Dumbo.
So my advice: do some research and get to know the FP attractions at all parks, then plan your touring accordingly by going from FP to FP with the minor/secondary attractions, various shows, parades, and/or food stops to take up the lag times between "return times."
Hey, it worked for us like gangbusters! We pretty much got to see everything we wanted to see.