I would tend north a bit. Choose whether to pass north (Canada) or south (Ohio, PA, NY) of Lake Erie. Enter very bike friendly western NY. Decide on flat (Erie Canal Towpath) or hilly (anything to the south of that.) Turn right when you hit the Hudson River and follow the river valley south to NYC. Check out www.roberts-1.com for routes in the valley. Cross into the city on the George Washington Bridge.