Also, not terribly important, but Continental offers free meals (in both Y and F) on most flights, while Delta does not on most. Continental F domestic service is still OK, while Delta F is sometimes nothing more than a wider seat.
If you have money to blow and time is tight, there is helicopter service to the airports from Manhattan and other locations. Continental also offers mileage for certain Acela and northeastern Amtrak routes. Continental also gives 50% bonus for Silver while Delta offers 25%.