Nice, but damn that's a lot of travel. Only a long weekend in NH...are you flying?Kids Spring Break Trip planned: DC for two nights, staying with my sister's fam in Philly 1 night, 1 night in Manhattan, and then a long weekend in New Hampshire.
For northern New Hampshire, I strongly recommend: Franconia Notch, Mt. Washington (obviously), Flume Gorge. The Cog Railway is an amazing trip, unless you want the bumper sticker for driving up. Portsmouth, NH is a really lovely seaport as well, Strawberry Banke is a great way to spend a nice afternoon.