The Google Maps thing's fine for displaying the route (and as all the regulars know, route subject to change on the night anyway), but if one actually wants to use it on a GPS, it's absolutely useless because there's no way of getting a file downloaded (there is a third-party browser plugin that enables downloads, whether it works or not...pass). All the major route mapping sites have their pros and cons, but
ridewithgps.com is probably the best overall for ease of use, download options and so on.