My poor man's GPS system: ( I'm serious )
I go to Mapquest and Zoom in on the area or route of interest. I print out one section and then move the map to the next area along the way and then print that section out. I trim the sections and use clear scotch tape to piece them together.
It takes a little time, but you end up with a real nice custom map piecing all the sections together. They will align perfectly. You can make an 11 x 17 color copy of the pieced together map even with highlighter marks on them at a place like Kinko's for about a buck and hand them to friends as well.
Fold them once or twice and you can have them set in the tank bag window ready for easy reference. I have maps with good detail that will cover sections of my trip to Spokane. You should be able to make a pretty good map covering Spokane and the northern parts of Idaho so anyone in the know of good roads in that area can help you mark your enlarged map.