There is a lot more to New England than big cities and the Maine coast, you know. We do also have rural areas in abundance, and mountains, and small towns, and state parks that are fairly reasonably priced to camp in. I'm not unbiased, not in the least, but I think New England and upstate New York would make for a great trip.
I might suggest as one possible rough itinerary going up the seaboard cities (Washington DC, Philly, Boston, etc.) on the way north, also stopping at Mystic Seaport, possibly Newport, RI, and Cape Cod, maybe about 2 weeks or a bit more. Next a week meandering up the Maine coast, including a few days at Acadia and Bar Harbor, preferably making it all the way to Quoddy Head. Then a few days in the White Mountains, a few in Vermont, and over to New York. In New York, maybe Watkins Glen for a day, Letchworth State Park for a couple, a day or so at Niagara Falls, and then start heading south. Knoebels (in PA) for a day, and take a week or so meandering down Skyline Drive and the Blue Ridge Parkway to get back. That probably works out to be a week or two too long...but it might be my starting point.
Just GSM NP, the BRP, Skyline Drive, and then PA and upstate NY would also make for a fabulous trip, for that matter.
