I agree, Mud. Learning to "read" the land and identify the patterns of human activity is a fun challenge, both at the site and by using some of the cool information tools that we have at our disposal nowdays . I use my tablet a lot for that - in addition to Google Earth, I use a program called 'Backwoods Navigator' which I like a lot because you can switch between numerous map sources, both imagery (USGS, USTopo Aerial, OpenAerial, etc.) and Topos (Accuterra, CalTopo, USTopo, ARCGIS, etc.) and layer them. Your marked waypoints show up across all of them, so it can be an interesting way to research a site.
When I head for the university library, the tab comes with and I mark potential sites in the program and take notes in a little free program called 'NoteSync' that automatically synchronizes them between the tablet, Google Docs, and my Home computer (in both directions). Different maps have different historical features marked (like some of the old trails in this area). Just another fun part of the hobby, and a great way to spend a wintery day, especially if you enjoy local history.