+1 for North Pole, we prefer the 100 Acre Woods area. It's in Wilmington, near Whiteface Mt and about 8 miles from Lake Placid. There's also a KOA there but we've never stayed at it. There are several State campgrounds nearby but they don't have any hookups.
We stayed at Cape Anne campground in Gloucester (so-so) and took the train to Boston. Last summer we did a night at Boston Minuteman on our way to Maine and we'd stay there again if we wanted to do the area.
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Just DW & me......