Honestly, why would I EVER choose an airplane over a train? Or an airport over a train station?
We scored some pretty good fares on Amtrak (months ago) for a visit to NYC originating in DC. While I've traveled by train in Europe, I hadn't done so in the States before this trip.
The reasons Amtrak rocks, or why I prefer it to air travel:
1. No check-in counter + no security screening = no long lines with crabby people. I'm not a big fan of those oh-so-friendly & helpful TSA agents, either. They are not in the train stations...yet.
2. Tons of space on the train.
3. No turbulence.
4. Dining car. We didn't even use it but I know I prefer it to in-flight "meals."
5. No stressed flight attendants. Not all of them are cranky...but too many of them tend to be a bit snippy, to say the least. Except for the initial ticket check, we really did not interact with the train attendant.
6. Free wifi.
7. Very liberal baggage policies and no need to check the big bags.
8. Did I mention the space? We could have fit a third person in our seats for two.
I'm not sure if it's an affordable way to travel in general. While the actual time traveling by train is likely more, 3.5 hours on the train from DC to NYC, my guess is that the time for air travel, including time in the terminal checking in, proceeding through security, and claiming bags would likely be a similar amount for a trip like this one.
Amtrak is the way to go, my friends.