As I mentioned a couple of times upthread, I often have to travel the NYC to DC sector. There is NO way I would fly this, given the stress and waste of time getting to DC/NYC airports, dealing with security lines, crowded airports, cramped seats etc. Amtrak is the ONLY way I travel this.
If I recall correctly, the travel time is 2.5 to 3.3 hours. Getting/to from LaGuardia, EWR, or JFK and the same for BWI or IAD (DCA is ok) adds to your travel time, as do check-in if you have bags and security.
It’s not scenic, but it is so relaxing being on Amtrak where, even in coach, you have nice seats, wifi, can work etc. I would never fly this route.
Now, I am looking for scenic train routes, where time is not a factor. I appreciate the downsides, but there are downsides to air and car travel too.