My DS5 gets his map/location obsession from his grandpa. My dad is map-obsessed and I remember going with him to various places to get topographical maps that were very detailed. He would have the exact longitude and latitude that he wanted. So, maybe a topo map of a local area, explain how the lines work?
Also, my dad has a series of DeLorme atlases for the states. There is one book per state, I believe they say Atlas and Gazetteer on the cover. Those are fun because they are more detailed than the state highway maps, so you can find pretty cool information.
Have you let him play on Google maps? We love looking at places and viewing the maps at different details, doing the satellite overlay, checking out the street view. Especially fun for places you're going to visit, or have been, checking out Grandma's house, etc.
