I would worry more about snow and ice more than rain in November. Are you doing all of the Parkway or just parts, If you like wine and old mills there is Mabry Mill and Chateau Morriste (not sure if I spelled either right) in Meadows of Dan, you could also jump off the parkway above Roanoke and visit the D-D Memorial. There is Biltmore House in Ashville and a few falls along the route.