I usually plan a tour with Google maps just because it's easy to do on the computer. Once done, I'll collect the state maps, mark out the route, and cut, tape, and fold into a convenient size.

Lately, I've conquered the gps, and route planning for it, on www.mapmyride.com. I augment the state maps with routes loaded into the gps. That's more for entertainment value than anything. When in conflict, always follow the state maps.

Here for a tutorial on moving a computer planned route to a gps.

With the right electronics(Ipod, etc), you should be able to create e maps from Google pages and review when needed.

Lots of people like the Adventure Cycling Association maps for their specificity for the needs of touring cyclists. If you plan on mostly camping, they may save you nearly as much as they cost by pointing out low priced or free camping spots.