So, as a Honda/Yamaha/Suzuki/Kawasaki dealer, it's kind of tough for me to endorse a HD product, but I have to admit this is one I like and have used for years.
http://www.harley-davidson.com/wcm/Content/Pages/Ride_Planner/Ride_Planner.jsp
Great site for planning out long rides. Lots of them already suggested by other riders. Good stuff!