I only live twelve miles from the Philadelphia Airport. It is just too easy to leave out of PHL. As I mentioned, at 6:00 AM on a Saturday morning, it was only a twenty -two minute drive from my house to Terminal A.
Takes me at least 2 hours to drive to Newark Airport - sometimes more if traffic on the Turnpike is jammed up. Amtrak looks good on paper, as the train ride is only about an hour from Philadelphia Amtrak Station to Newark Airport. I have tried taking the train from Philadelphia to Newark Airport, twice; and it did not work out very well. The first time, the train had some problems, and got us to Newark Airport just in time to miss our flight to London. The second time, traffic in Philadelphia was so bad, that we got to the Amtrak station just in time to miss the train to Newark. I had to ask the friend who drove us to 30th St station in Philadelphia to then drive us to Newark Airport. He was pretty pissed off, even though I brought him a tank of gas as he had to get up early the next morning for work.
having aid all that, it is still easier than trying to get to JFK Airport in New York.