Thanks for everyone's inputs and recommendations. As it happened, I ended up using Amtrak. Although I would have preferred to drive, and preferred to save the Amtrak fare, driving would have consumed about 12 hours or more of my time. On the train, I was able to read, nap and eat, so it was more relaxing and a much better use of my time. Plus it seemed to me that consuming the energy to haul a 4800 pound automobile for 600 miles was not very responsible when the train was going my way anyway.
Under different circumstances I would drive. If my spouse were with me, it changes the economics considerably, plus we can spell each other driving.
Thanks again for the thoughtful comments.