I was talking with my GF tonight, and was wondering how to spend my 1-week vacation this year. So I hit upon the idea of taking a car trip up the east coast from Norfolk, VA towards Maine.
This will probably happen towards next April, so not super worried about snow
If you are coming up in April, and make it up to Maine, New Hampshire, or Vermont, snow is still an issue
People are still skiing in the NH White Mountains in April sometimes, certainly in Tuckerman's Ravine, and there's still going to be snow followed by mud, along much of the AT through VT, NH, ME if you come up that far.
Having said that, it's awesome hiking up there. Try the AMC:
www.outdoors.org for some good planning info. Hiking some of the Presidential Range in the White Mountains National Forest, or doing Katahdin up in Baxter State Park in Maine would be great, but, you really need to be prepared at that time of year. On Katahdin, April's probably going to still mean winter boots, crampons, ice axes, etc. If you go up the "Knife Edge" trail in April, you'll never forget it. (Assuming you live) It's the northern end of the AT.
As your planning gets crisper, and you decide what states you'll be visiting, let us know. If you make it to New England, I can give you some help I'm sure.
What a fun project to work on over the winter!