George,
Take 340 out of Front Royal to Frederick, MD and pick up 15. take 15 to Gettysburg and pick up 30 to Lancaster. If you have never been through Amish country go through Lancaster on 30 and get off on 340 (Philadelphia Pike) and head through Bird in Hand and Intercourse. In intercourse take 772 north to 222 which will take you right to Allentown. There are some lights on 340 and 15, but not bad. Amish country is slow moving, but not that far and once you turn onto 772 it is a nice ride up to 222. I just came back to Virginia on that route last month.