Along the Connecticut River, Southern New Hampshire is located near Westmoreland, New Hampshire. The trail is primarily used for scenic driving and is accessible year-round.
I have traveled this route a number of times over 50 years. Despite how busy the road is in any drivable season, it is a classic for scenery of mountains, forest, river, etc. It is spectacular in the fall, when it is incredibly busy. Somehow, word about New England foliage leaked out. In a good year, it is better than you've heard. In a bad year, it still beats almost anyplace else.