check to see if there are any "fall tours" maps. those are planned on more scenic minor roads so that people can see the changing colors of fall. there might be something like that for some east coast states, eh?
barring that, just look for maps that include minor highways or county roads and see where they go. maybe even look for "bike trails" on highways or county roads. if they're safe for bikes (and ecouraged for them), they should be fine for mopeds, too.