>>>I know there is good train service between Boston and NYC. But maybe the stations are too far away on one or both ends for that to be a practical choice.
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>>I know about the train service. But I like the convenience of driving (time-wise, etc.).
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>Train between NY and Washington, DC takes 3h. I would expect about 3h from Boston to NY too.

And the difference is that this is far faster than flying. Airplane may take you from NYC to DC in less than two hours, but that's just airport to airport. Add about an hour or two to get to/from the airport NY side, about an hour DC side (that's off peak hours!), plus at least 45 minutes that check-in, security check and boarding take (specially if you have to carry your own boards, hammer and nails ;). With a train, arriving at the station about 20 minutes in advance is enough, and it takes you straight downtown.

For a couple of years I was traveling from here to NYC several times a year, and since we live south side, the train would leave me north side - about 30 miles from home, and then they'd have a bus to take us further, which took two hours for those 30 miles! The train was also ridiculously slow through Richmond, where it took half an hour between the two stations there, where the physical distance is no more than six miles. It crawled/dragged, and so it did on my nerves too.

And then I discovered the Chinese bus - ivymedia.com sells the tickets, and I remember they have a line from Boston to NYC, station is around Forsythe and East Broadway in Chinatown on Manhattan. The prices are ridiculously low, but they'll still give a discount for a round trip.