This is a minor point, but Amtrak arrives/departs from the Moynihan Train Hall now, not Penn. It’s a much nicer place to wait, and only passengers with that day’s ticket are allowed in the waiting area. It’s across the street from Penn.

As for length of the trip, Acela was under 3 hours each way when I did it in December. I love trains and would love an excuse to ride once a week but it would probably get old fast.