Kick ass, another Washingtonian!
IMHO, Manchester, Nashua, Concord, and Portsmouth are the best for being pedestrian friendly, although most towns with more than 5,000 seem pretty well set up for foot traffic. I believe that Manchester also has the most extensive mass transit I've seen, though in Portsmouth, you don't really need any. In fact, some folks in Manch and the seacoast just get around by bike, which is fine. I've done it in Seabrook (as do others) though there aren't really solid accommodations in Seabrook for bicyclists... other than the side of the road and very well built sidewalks. It's more foot friendly that bike friendly--except for short trips to the beach, which are great.
Actually, Seabrook is a bit like a smaller version of Ballard, if you've been out that way. It's kind of a small, ocean front town dealing with big box development.
But yes, New England towns really are set up much better for foot traffic--mainly because most of the streets and blocks were set up at a time when most folks didn't have cars. Before conventional, euclidean zoning, developers had to create the beautiful, mixed-use town centers if they wanted to attract pedestrian shoppers. Those town centers are everywhere, and many residents either don't have cars or rarely use them.