When you build maps (combining states) for iGuidance, it can only use one of these maps (of multiple states) at a time.
However, you can have more than one map in your PDA. The map data is stored in a directory called Maps. You can have multiple directories of maps on the PDA - you just need to rename the ones you are not using to something else. For example, I may have a directory with the map around home and another for when I'm traveling. The one I currently want to use is named Maps, the other one is named to tell me what it contains (e.g., Maps-NJ-NY-VT). When I need to use the other maps, I shut down iGuidance and change names (Maps -> Maps-Home, Maps-NJ-NY-VT -> Maps). This way I can have multiple maps in the PDA without needing to regenerate them all the time. I also save them on my PC this way so that I can just copy them to the PDA.