If you don't mind flat routes, and are looking for solitude, I would recommend the following (Both sections of the Northville-Placid Trail):
From Long Lake to LP -
38 miles. You'll encounter no roads in this section, except for about a mile of hiking on the old Ward Brook Truck Trail, a gowing-in dirt which has been closed for years. The trail folows Long Lake, Cold River and the Moose and Chubb rivers, With a peaceful mecca at Duck Hole.
My second recommendation is From Piseco to Wakely Dam -
33 miles of pure roadless solitude, filled backcountry lakes and Loons calling in the evening.
PM me with your Email address if you'd like an NLP trip planning spreadsheet with all the mileage and trail details.
Rick