I'll try to get you started. First, the layout of the land. The Green Mountains run the length of VT, the Berkshire "hills" run north/south in western MA, and the Taconic hills run along the NY/CT border. I don't know MA and CT well enough to offer specific routes, but I believe you basically have 3 choices. You can follow the CT River through CT, MA and VT all the way to VT's northeast kingdom, you can go up the spine through the middle or you can go up the Hudson River valley in NY and up the east side of Lake Champlain in VT. There are many nice secondary roads that follow the CT River in VT and NH. I think just following Route 5 would be decent. It connects small river towns and most of the traffic is on the parallel interstate. Riding through the hills would be scenic but definitely more difficult that the other two options. While you're not climbing mountain passes, the hills are sometimes quite steep and you could probably easily accumulate 3000 vertical feet in a 50 mile ride. It is doable, but you'll earn your miles. The scenery from Route 100 in VT is beautiful, but it's like a rollercoaster, kind of busy and often there is not much of a shoulder. There are some nice roads between Poughkeepsie, NY and Albany, and the area from Bennington (like Route 30) all the way up to Burlington is great riding. From the VT side near Crown Point you can follow Lake Champlain on rural, county/town roads almost all the way to Burlington. Check out
www.champlainbikeways.org. Cycling in the northeast kingdom of VT is superb. You can download a nice pdf booklet from
www.nvda.net/Transp/bikeped.html. If you want more details or have questions on the Hudson Valley route, send me a private message and I'll try to help you further.