The Amtrak route I use doesn't offer first class cars, but I can compare Amtrak and flying.
Security is almost non-existent. Nobody checks your person or bags. (Well, if you acted suspicious, I suppose they might.) No no TSA lines, taking shoes off, etc.
You manage your own bag, including lifting them into overhead bins. While someone may offer to help if you're struggling, you can't depend on that. So make sure you can carry and lift your suitcase.
Your seat on a train will be way, way larger than a seat on a plane, with more leg room. Every pair of seats has two electrical outlets. It's reasonably comfortable. In cold weather, don't sit too near the door; cold air comes in at every stop. I try not to sit right near the restroom.
There are two restrooms in every car. Unlike planes, there is rarely a line or a wait. Careful--the restroom is not cleaned during the trip and it's sometimes pretty yucky by the end.
You are welcome to bring your own food on board. (We always pack a lunch and snacks.) But if you can't, you can buy food and beverages in the cafe car, and some trains have a sit-down dining car.
It's standard for trains to run late, sometimes very late. We never plan anything for the same day we expect to arrive by train. We've been as little as 20 minutes late--or as late a five hours. You just never know. Often you're stuck behind a freight train that can't go fast, or delayed by an accident on a railroad crossing.
The view is often great. You see lots of derelict buildings that once served businesses that shipped by rail, lots of forests and farms, lots of open land. Pay attention to where the view is (my usual route runs next to a river) and to what direction the sun will come from. It's pretty hot sitting in the sun hour after hour, and you may not be able to move to another seat.
Bring a book, a device with games and/or entertainment pre-loaded, and headphones or earbuds. (You don't want to be the jerk watching a movie with speakers, and everybody glaring at you because they can't read over your noise.) There is internet on trains, but it's often slow or spotty, and sometimes disappears. Don't count on interactive websites to entertain you the whole time. I've been on trains worse than dial-up.
Came home on a train yesterday
· 4 months ago