In your travels another place you might want to hit - is brattleboro vermont - it's about an hour or so north of boston - maybe 2 -3 hours west of New Hampshire - and very pretty... It's got lots of quaint country stores and tons of stuff to do -
New Hampshire (Pan might twitch about their politics of the state) is anothe beautiful new england state - the lakes region - by Lake Winnipesaukee is gorgeous.. or MOunt Washington in the White Mountains though not sure if the auto road is open in early may - both regions are really lovely and worth seing.
Portsmouth NH is a coastal city - that's on your way down from Maine (You could go Maine, Portsmouth NH - then head weast to the white mountains and thelakes region into Vermont)
That area offers tons of bed and breakfasts...
RI - aroound newport is beautiful but RI really doesnt have that much more to offer - unless you like coffee milk...
