What kind of things do you want to do on the trip? The trip is about 500 miles and could be done in one day. One possibility is
Toronto to Niagara Falls and then west on I-90 to south of Rochester (New York) and then take NY 14 down along the Finger Lakes Then go west on I86 to Painted Post and Corning. Go south on I-99 and US 15 (which is a pretty drive) to Williamsport (Pennsylvania) Then you take I-80 east to I-476 and thence to Philadelphia
Mentioned in this answer:
