Central, Route 17. Both scenic and twisty, low traffic density, excellent road condition. Starting at 100, west from Irasville. Vermont's own legendary "Appalachian Gap", a world class twisty mountian pass features many knee dragging corners, one right-hander in particular just won't quit, covering about 200 degrees of curvature in an ever tightening radius. Take it easy the first time through, take note of hazards. A sport bike mecca on weekends, but also a major attraction for state police looking to fill speeding ticket quotas. Take note in particular that the route posts an "artificially" low 40 mph limit throughout, so you can really get nailed. Check out others areas nearby for waterfalls and other scenery.
Route 100. Both scenic and twisty, low traffic density, good road condition. Rt 100 runs North/South through the middle of Vermont. Very scenic twisty 50 MPH road running alongside the Green Mountains. Best time is beginning October, when the leaves change. You'll go through several small Vermont towns, and be on the lookout for a church supper. Ride to the top of Okemo, stop at the Green Mountain Coffee store at Stowe, visit the Trapp Family Lodge at Stowe, and take 108 from Stowe to Smuggs. Tightest twistiest mountain pass I've ever seen.