I remember a Bikepacking website had an article on the Gravel Growler, a loop from Burlington involving dirt roads and local breweries, as John Flores mentioned. There is a cross Vermont trail from Burlington to Wells River, about 90 miles, a lot off road. When you get to Wells River, you are right across from Woodsville, NH and the start of the Cross New Hampshire Adventure trail, about 80 miles of mostly off road riding to Bethel, Maine.
If you want to DIY, the Champlain Islands going north from Burlington are charming, smooth, low traffic pavement and the Green Mountains on one side and the Adirondacks on the other. Just about anywhere you go in Vermont will be pretty, some research on RideWithGPS will yield routes from cute to challenging, depending on the hills.