Welcome to BGH. I like the digital overlays provided by Huntdata for use in Google Earth. But some state game departments also (ID and CA offhand) also have downloadable free overlays that will at least show you the unit boundaries. If you know exactly where you are hunting you can get the USGS maps from the USGS. However, in Colorado and Utah, National Geographic makes a superior plasticky paper map. Google Earth is by far the best tool for remote scouting. If you spend enough time looking at your hunting area, you will be pretty familiar with it when you finally see it. But if you don't have landownership overlays, you'll need to at least have a paper map or atlas that has some landownership on it you aren't spending your time looking at private lands.

So first you'll want to have an idea of where you are going. So maybe an atlas is best to start with (Roads of Colorado is vastly superior to Delorme, which generally doesn't show private inholdings within a national forest). Find a place whose stats you like in an area that has sufficient public land for the type of hunting you plan on doing, then start looking at more detailed maps.