I am not a huge fan of a few parts of Route S in Lancaster and Chester Counties. To much time on SR 23 when much nicer alternatives are available. I understand why they do it, but that doesn't make it right.

If you go slightly off route in the area of Morgantown, PA you can camp at French Creek State Park. Nice place with lots of shade. There is even a swimming pool there. (Admission to the pool is $7 for the day.) From there, you can easily make down town Philly in one day using the Schuykill River Trail into Philadelphia. Route S crosses it on Pawlings Road. When the SRT ends, you can then take an old canal tow path to the Manayunk section of the city. After a short stretch on the road, you can then pick up another rec. path and ride that and/or MLK Drive (which is closed to cars on weekends) to the Art Museum, which basically the start of "center city." And, of course, you can make the obligatory run up the steps a la Rocky and have your photo taken with his statue.

Send me a PM if you want more details.