Get the best maps you can. The DeLorme atlases are OK, they work, but they don't have the fine detail of the USGS maps (but both are often a bit long in the tooth). For the critical areas, I like having the USGSes, and a chopped DeLorme for the less critical areas in BoB. But if you can afford it, USGSes for the whole thing- a map case made of PVC is bulky, but bugging out by car it is manageable.

By chopped, I mean cover and touristy stuff, gone. Remove the portions of the book you won't need. Fold them consistantly, and put them in something like an AlkoSak or similiar waterproof bag. I"ve got the top half of Vermont in package not a lot bigger than a deck of playing cards after that. It's a good place to put things like photocopies of your liscence, birth certificate and passport, and some cash, along with a spare compass.

Of course, never trust ONE map. DeLorme, USGS, USFS, local parks and recreation agencies, aeronautical and coastal charts, they all end up in my collection along with aerial and satellite photos. Better than just a map is to drive your major routes, best is to drive them all, and bestest is to walk them, learn where the short cuts are, where the river fords are, that kind of thing.

EDIT: "Bestest" is hyperbole, I know quite well it isn't a word. :P