Originally Posted by Adam1222

1. LGA is a DL hub and many routes ex-DCA offer connections via LGA.
2. Having done this route at least about a hundred times for work and family, there are a lot of factors at play, including price, time of day, ability to work on the train, and, for me most importantly, where you have to be on either end of the journey. If I have to be in Manhattan for work, train often makes sense. If I'm visiting my family in Nassau County, plane is often better, as the time to change to the LIRR is significant. And if you can't leave DC until 6pm or so, getting to the suburbs that night via train is much harder than flying.