I also booked Song fram LGA for a trip in May. $85 cheaper per person x 9 people made a huge difference. With the money you save, why not hire a nice towncar or limo service to drive you to LGA or JFK and take that stress out of the picture. Thats what we did. Also, most people fly on weekends, so the city traffic is minimal. Remember, Newark airport, although closer, is no picnic getting in or out, especially terminal C.
I asked the salesperson at Song why Newark airfare was so much more for basically the exact same flight. She told me thatalthough they fly to all 3 airports, the fees to use Newark are much higher than JFK or LGA. That will always make Newark more expensive.
I have never tried Allentown, but from what I hear, the exrat time spent getting there is worth it. Much less time and money is spent parking and chacking in to a smaller airport. The same goes for Orlando/Sanford.