Cooperstown isn't far off the beaten path.
Lake George is worth a day or two. The Adirondacks, of course. And Burlington, at the edge of Lake Champlain, what a nice little town. I have to recommend Vermont generally, what a beautiful, clean and tidy place. Stay a night (camp!) at Lake Willoughby in northern Vermont, closest we have to a fjord. Easy hike up the ridge that runs along the lake, spectacular views. http://en.wikipedia.org/wiki/Lake_Willoughby
Head north up to Montreal, spend a couple of days walking around, but save a few days to head up the St. Lawrence to Quebec. The old English/French thing is a bit overblown, you speak the universal language after all. 
Cooperstown would be about 1 hour 15 mins from the I87/I-90 interchange so it's a bit out of the way.
Lake Placid and Saranac Lake are well worth the stop if you're heading up the Northway to Montreal. Ausable Caverns as well.
If you're into outdoors stuff, the Adirondacks are a go-to spot. I can recommend quite a few places but my favorite is Indian Lake Islands campground. It's a bit "hardcore" and if you rely on a camper or cabin to do your "camping" then it isn't for you. But if you can tent camp and enjoy fishing, Indian Lake is pretty much the best there is IMO.
