Am I crazy to even consider this time of year (end of March/begining of April)..we have always gone Oct or Nov..but times are changing in our household so not sure we can do that for our next vacation.
How busy is it?
What about the end of August--worth it with the crowds/heat??
Or are most kids back to school by then & it is okay??
We were there August last year, would have been returning home 1 year ago today.
As they say, Disney is great anytime, however, we will never return in August, just because of the heat. We live in Southern Ontario, and have our share of Hot&Humid, but there is no comparison to that
The crowd levels were OK, EMH at MGM, and our last day at MK were bad(eg, the Fast Pass return line for SM was a 50 minute wait.
It rained everyday, although not for long, but your thinking, OK, now it's going to cool off..........not so.
You also risk Hurricanes at that time, one went through our 3rd day there, but didn't amount to anything, but they warned you, and changed the hours around just in case.
DS doesn't do well with heat, and and ended up dehydrating(or mild food poisoning

) and was out for the entire next day.
We will be going this year, Nov10-17, our first trip home as DVC, BWV.
Were there Nov/04, weather was great(mid 70's), only 1 small rain shower, and low crow levels(left the Sat. before US Thanksgiving and the hoards were just arriving as we departed), hoping for the same this year.
As for March Break, we will be going this year '08 staying AKV.
Not real sure what to expect about crowds, but it maybe just me, DS 12, and DD10, so we may just hit things early, and hang out with the animals, by the pool.
Friends of mine went Christmas, March Break and Easter, and said by far Easter was the worst.
This year however, March Break falls the week before Easter, so many people are pulling the kids out of school for the 4 days between March Break and Easter, and getting the full two weeks off.
I'm sure you'll have a great time whenever, but just some info.to help you plan(perhaps too much info, but hey, that's me.)
