I just did the RailPass thing last year and it was one of the most amazing experiences of my life. Went from California to Chicago and then New York, and then back the other route (there are 3 cross-country routes, I believe).
As others have said, the RailPass just gets you a certain number of on-and-offs, but it’s totally worth it for cross-country trips. I did the 2-week one, but they have 7-day and 30-day ones as well. It is an additional upgrade to a sleeper car, but if I remember correctly, it was a MUCH better deal to go from a RailPass ticket to a sleeper car than to pay for the sleeper car outright. I am not completely certain of the math, though, so double-check.
The thing about the RailPass is that Amtrak is VERY good about schedule and route changes. Stop somewhere you like and want to spend a few more days there? No problem, call them up and they’ll change your ticket for no charge. At most you might have to head back to the train station before departure to pick up the new ticket (their e-ticketing system isn’t very good). Try doing that with airfare.
And yes, you do have to plan on connecting routes and transfering a lot, but that’s part of the fun
I ended up moving to a city I was passing through, which I never would’ve even visited if I were flying.
If you get delayed somewhere overnight, call guest relations and they’ll typically reimburse you for a hotel stay.
If you have good credit, consider signing up for the Amtrak Rewards credit card before you buy anything, and then use it for all the stuff on your trains, upgrades and all. You get cool signup bonuses (like free upgrades or rides) and a bunch of points.
There will be no wifi onboard (except along the Eastern Seaboard, where Amtrak has all their fancier trains. The rest of the system is run on shitty old equipment, decades old). Cell phone coverage will be spotty. Plan for it. There are chargers on board though.
That’s just the logistical stuff up there. The actual experience is quite surreal. Depending on the time of the year, you’ll either see a lot of retirees, some people from a religious cult (they remind me of the Amish, but I forget their particular denomination… I think they are not allowed to fly but can travel by train?), or maybe youngsters on a sojourn. Very few people travel by train anymore, and those who do typically choose to on purpose because it’s such a different experience. The view car is awesome, with wide bench seating you can lie down and read on, or just watch the landscape roll by. The dining cart (all your meals are included if you go for a sleeper car) serves acceptable food, nothing to write home about but better than airline food. You get seated with strangers at shared tables so you can meet new people and learn cool things about them and why they travel by train. People from all over the country and the world ride Amtrak, either for nostalgia or novelty.
It’s definitely a very inefficient way to travel, but a unique one that’s worth experiencing at least once in your life. Whereas in Europe it’s a way to get from points A to B, here it’s just a way to take a long, moving vacation through some beautiful countryside, often even without roads. Of course, you can only do it if you have time, and that means you don’t get a lot of time at your actual destinations. The journey itself is what you’d have to be interested in.