You must be a AAA member to use their TripTik service, which is available online, but I find them to be by far the best. MapQuest and Yahoo! Maps have gotten me in hot water by making errors, and also often don't give the most efficient routes. It is possible that the routes they give are the shortest distances, but often take longer due to traffic patterns (I can think of at least two examples of this within ten minutes of my house).

In contrast, AAA has never steered me wrong, supports multiple stops, and has features like the ability to select the easiest route to drive, and nearby attractions and restaurants. They also provide maps for every step of the way and highlight your route on them.