Now is the perfect time to go.Trees with fall foliage line railroad tracks in Holyoke, Massachusetts.Credit: iStockphoto/Getty ImagesKey PointsAmtrak’s Valley Flyer travels from New Haven to Greenfield in 2 hours and 48 minutes, offering a traffic-free way to see New England fall foliage.Late September through October brings prime leaf-peeping opportunities, with western Massachusetts typically reaching peak color in early October.Stops includin…