Instead of driving through the middle of Delaware to Philly consider going to Lewes DE and take the Cape May-Lewes ferry to Cape May NJ. The boat ride itself is pretty relaxing...just make sure you make reservations for the ferry because there are limited spaces. Visit the Cape May lighthouse and hit the beach. There are a lots of B&B's in town where you can book a one night stand. Jackson Street is a good central location for walking to the beach and restaurants like the Mad Batter. There is also a patriotic sunset celebration at sunset beach on the bay side if your into that. If you have young kids the boardwalks in Wildwood and Ocean City are worth a stop. If your into gambling Atlantic City is on the way. To complete the detour take the Garden State Parkway to the Atlantic City Expressway into Philly. Looks like a fantastic trip!