So many options in all of those states. But here's a bit of a POV from a Boston guy;
• If you're visiting anything on the shore during the summer season, do it midweek, go inland on the weekends unless you love traffic.
• Maybe I'm just sick of it, but I don't find Cape Cod specifically photogenic.
• Others have given a lot of advise on Maine, and you've probably seen the other post on that subject today,
http://www.uglyhedgehog.com/t-521305-1.html• Don't discount Rhode Island. Yes it's small, and we all make fun of it, but there are some nice places. Newport is great to visit, but hence the advice on sea shores and weekends.
• I'm a bit biased towards New Hampshire. Not a lot of big tourist areas, but some good hiking without being a mountain climber.
-North Conway is a good place to stay, then you can explore the mountains, rivers and ponds from there. Eastern Maine is also just a bit to the east. The Black Cap trail off of Hurricane mountain road gives a great view as you're 1200' above North Conway with views across the valley. And most of the vertical is gained by driving to the trail head.
-North Woodstock is a bit sleepy in the summer, but once again, you'd be 10 minutes away from some nice photo opportunities. Nice hikes, an arial Tram at Cannon Mountain, and the west side of Mount Washington just to the north.
• Vermont is really nice too. If you enter from NH, route 4 just off I-89 brings you through Quichee Gorge, and then to the picturesque resort area of Woodstock (yah, we like that name for towns in New England) North of US 89, there's Montpelier, Stowe and the farm country if you head north on Rt100, and then Burlington along lake Champlain.