end of february travel or last week in april 2016? , passover is the last week of april and northeast schools are off
If you can avoid traveling at a time when schools are off, I highly recommend it. I'd go with the end of February.
When deciding travel days the Crowd Calendar is always my first stop http://touringplans.com/walt-disney-world/crowd-calendar
Don't love periods when schools are off... but Jan-Feb is the period that sees he most ride refurbs, and the weather is so cool that swimming at your hotel (and the water parks) is chilly.
Massachusetts will be off the week before, but yes, New York and New Hampshire have that week- don't they?
The end of Feb will be post Mardi Gras. Not sure about spring break as I no longer have school age kids. So it should be low crowds. Agree with Brian, look at the CC and see what it looks like. Keep in mind a "slower time" also means shorter park hours.
End of February will be New Hampshire school vacation as well- right?
One thing to bear in mind about school vacations is that the schedules for school systems that can have a significant effect on crowds are taken into account when making the CL predictions. There was a good TP Blog post about this, but I can't find it right now...
EDIT: Found it! They track the 100 largest school districts http://blog.touringplans.com/2015/03/05/spring-break-2015-crowds-walt-disney-world/