The United States is known for a lot of things, but its amazing passenger rail system isn’t one of them. At least not since the late 19th/early 20th century, and not in comparison to some other countries that have developed truly modern passenger rail systems.
With that said, it is possible to travel by train across the entirety of the U.S., and some even recommend it.
I did a trip a few years back from Providence RI to Portland OR. I loved every minute of it, and would do it again in a heartbeat. … I took books to occupy my time, and didn’t crack the back of one of them. There was more than enough going on outside the window, inside the train, or down in the club car to keep me well-entertained. ~EnricoV
I enjoy travel, watching scenery pass, and waking up in a completely different environment each day, but it’s “slow” and not for the short of attention span. … One thing I will say, you will see parts of America you didn’t know existed. Who knew there were antelopes up north near the Canadian border! ~threepatchproblem
But even though long train trips are generally recommended by the travelers in this thread, they do offer plenty of caveats and suggestions to make the trip more enjoyable.
I would suggest getting at least a roomette. They are somewhat pricey and a little small for 2 people. (the seats face each other sharing the same legroom) However on longer trips I think it is worth the cost. ~Alaskan Mutt
I’ve gone 1/3 of the way across the country, and the best piece of advice I can give is: bring sleeping pills. Also, be sure to try Amtrak food because it is actually quite good. ~sidburn
Personally, I’m not sure I’m completely convinced of the merits of Amtrak after reading this discussion. Then again, many travel to Russia to partake of the Trans Siberian Railway experience ala Karl Pinkerton. Maybe a warm-up on a cross-country U.S. trip would be just the thing.