Once I knew where I was going, there wasn't any question about how to get up there. My goal was to spend as much time as I could zigzagging back and forth across the ridge that separates New York from Connecticut and Massachusetts. The roads that cross the ridge vary from little one lane roads with no yellow line to fairly large US highways. You'll sample many of them as you work your way up north.
The route starts at the intersection of US 9 and New York 448 about 1.5 miles north of where US 9 crosses I-287. This is just on the eastern end of the Tappan Zee bridge in Tarrytown, NY. What I like about the beginning of the route is how it gets you up and out of the populated part of Westchester County and on to some very pretty back roads without ever having to pick your way through any of the towns. One of its secrets is that the route follows the roads that circle the reservoirs that make up the New York City water supply. From NY 100 you'll get quite a view of just where the water comes from. Once you cross I-684 you can start counting just how many times you cross state lines, I bet you won't be able to keep track.
If you're inclined to go hiking in the woods, stop at Bash-Bish Falls State Park and take some time to look around. You'll find some very enjoyable hiking trails. After you pop out into civilization you'll be treated to a quick tour of Great Barrington. I thought about routing around it, but it is a quaint town.
North to Great Barrington Mileage Total Leg 0.0 0.0 Go East on NY 448 from US9 in Tarrytown 1.5 1.5 LEFT STOP - Follow NY 448 4.0 2.5 STRAIGHT LIGHT - Beech Hill Rd. 5.8 1.8 RIGHT STOP - Pleasantville Rd. 7.5 1.7 LEFT Hardscrabble Rd 11.8 4.3 LEFT STOP - T - Quaker Rd. 12.0 0.2 RIGHT NY 133 East - STOP 13.6 1.6 LEFT Seven Bridges Rd. - LIGHT 14.6 1.0 RIGHT STOP - T - NY 100 North - Follow NY 100 24.4 9.8 STRAIGHT Join US 202 North 24.8 0.4 STRAIGHT Join NY 116 East 30.4 5.6 LEFT June Road - STOP 32.7 2.3 RIGHT Bloomer Rd. 32.9 0.2 LEFT Starr Ridge Rd. 35.6 2.7 STRAIGHT LIGHT - Join NY 22 North 39.4 3.8 RIGHT Putnam Co. 65 North - TO: Putnam Lake 41.8 2.4 RIGHT YIELD - PC 66 East 42.1 0.3 LEFT Fire Station - PC 67 North 44.1 2.0 RIGHT Quaker Rd. - T 45.1 1.0 LEFT STOP - T - CT 37 North 52.5 7.4 LEFT CT 39 North - LIGHT - "Rizzo's" 57.1 4.6 LEFT CT 55 West 61.3 4.2 RIGHT STOP - T - Duchess County 6 North 65.9 4.6 BEAR RIGHT Y - Across bridge - Poorly marked. 67.6 1.7 STRAIGHT STOP - Join DC 4 70.9 3.3 BEAR RIGHT Y - DC 4 Cont. - Don't go down DC 105 72.0 1.1 STRAIGHT Join DC 3 73.0 1.0 RIGHT STOP - T - DC 2 75.6 2.6 BEAR RIGHT YIELD - CT 41 North 80.2 4.6 STRAIGHT STOP - Around Circle 80.4 0.2 LEFT STOP - CT 361 - Becomes DC 62 86.6 6.2 STRAIGHT LIGHT - DC 62 Continued 89.8 3.2 STRAIGHT Join DC 63 94.2 4.4 STRAIGHT Join Undermountain Rd. 96.3 2.1 RIGHT STOP - T - NY 22 North 100.4 4.1 RIGHT NY 344 - Follow NY 344 into Bash-Bish Falls Park 104.3 3.9 RIGHT STOP - T 105.5 1.2 BEAR LEFT Follow the pavement 106.1 0.6 LEFT STOP - T - Church 114.2 8.1 LEFT STOP - T - MA 41 North 114.4 0.2 RIGHT STOP - T - MA 23 East - Follow MA 23 118.5 4.1 LEFT US 7 North - Follow US 7 into Great Barrigton