Well, that settles it for me. I was three days on the train to Seattle (departing from Osceola) because of long layovers in Sacramento, both ways. Next time I’ll start in Minneapolis.
I did this years ago, from NYC to Tampa. It was an interesting experience. This was about 20 years ago so this may not apply now, but my advice is to dress warmly or bring a blanket or something, because I nearly froze to death at night on my trip, which I think was in the spring. Also, don’t depend on Amtrak to provide you some yummy food. I didn’t want to go to the dining car, so I went to the snack bar thing, and every single sandwich in there was about 5 days past its sell-by date.
Train rides are cool, though, and I don’t regret doing it. I also read an entire novel on both legs of the trip, and it was nice to have all that time to just sit and relax and read and look out the window.
Over 30 yr ago I took a train from Oregon to Detroit. It took 2 or 3 days, and I encountered every possible quality of passenger car during the trip. there were some nice ones and some cold and dirty ones. Same with the train stations. Bring some portable food with you to cut down on having to eat from vending machines. This may have changed since my experience. Overall I enjoyed the trip, and the motion and the track noise helped me sleep. I love trains.
I took a bag of apples but that was in the days before granola bars 
It was great. It started in the late afternoon so we were sleeping during boring Northern Minnesota and Eastern Montana. Just as it started getting pretty it was daylight, and it was broad, beautiful skies until we got to mountains. I bored my now-husband to death by making up stories about every ramshackle abandoned house (the stories all begin with the bank foreclosing and Ma being forced to sell the good silver).
The in Havre we had a 45 minute stop wherein everyone ran to the nearest bar and ordered pairs of drinks and bottles to go. It was such an adventure.
Yeah, my last trip to Chicago I witnessed an obnoxious passenger put off at some rural station because he couldn’t light up any-damn-where he pleased.
I’d just go by plane but I’m extremely biased where Amtrak is concerned. I used to do 2 routes fairly regularly. In college I used to take the train from Montreal to Syracuse to visit my boyfriend in Ithaca. I had to do a stopover in NYC. Then in law school I sometimes made the mistake of taking Amtrak down to Urbana-Champaign.
My gripes are many but they include extreme slowness, stopping on the tracks to let a freight train go first, endless delays and breaking down on the tracks. I’m so cynical about Amtrak that I’d posit 21 hours as a guesstimated time. You’d have to tack on 7 to 8 hours for bumbling, delays and waiting on the tracks for a freight train. I remember the last time I took them I was sitting in Chicago fuming that an 8 p.m. train didn’t leave till 11:45. I had a take-home test due the next day for Contracts and I didn’t even get back into C-U until early morning.
I also can’t tell you the number of times I’ve had to endure breakdowns on the tracks between Chicago and Chambana.
Incidentally, I was interviewing at Penn a couple of months ago and had to stopover in Chicago on my way back to Los Angeles. It’s less than 2 hours long as a flight. Fly Southwest if you’re nervous about airplanes.
I always had good luck with other passengers on Amtrak (as opposed to a trip on Greyhound that wound up with people getting kicked off somewhere random in Baltimore) but the best had to have been the night I got on the train to Chicago and found the car had myself, a few other people, and a whole extended family of either Amish or Mennonites. That was easily the quietest ride I’ve ever had.
I was on a train fro 60 hours from Moscow to Tashkent, Uzbekistan and several across Europe and China. Seems like it’d be a fun trip if they have WiFi.
The last time I was on a train I was slightly motion sick. It was a good thing it was less than an hour ride. Can you handle that long of a swaying ride.
I did a 28 hour train trip across India a few years ago, and it was great- of course I had a seat that turned into a bed, guys selling samosas and tea coming through the carriage every so often and a good book. I’d take that trip again in a heartbeat.
A few years before that I travelled from Budapest to Thessaloniki by train- I think about 18 hours or so. That was spent bolt upright in a compartment with a guy who kept trying to feel my friend’s boob, a family with all their worldly goods (including some chickens), a crying baby and no A/C. I wouldn’t wish that journey on my worst enemy.
If you can lie flat, have something to entertain you, good food, don’t mind feeling grubby when you arrive and don’t mind sharing your space with whatever person Amtrak puts you beside- go for it!
I’ve ridden Amtrak to-and-fro the South and even the DC line within the past couple years and found it a positive experience overall. Bring an MP3 player with a charger, some books, maybe a magazine or two, some snacks, water, blanket, pillow, jacket, NyQuil maybe, you should be alright. Even though I generally prefer flying, I think my experience with Amtrak has actually been much more positive. As long as you’re not in a hurry to be anywhere --I’ve actually shown up early on some trips, but expect delays and be OK with them. There’s a lot more room, there’s smoking stops if you’re so inclined, the staff seems to be much friendlier, if the person in the seat next to you is a creep (or a crying baby) you can change seats, or better yet, go to a different car.
A few relevant SDMB threads, some that use the same route you’re about to take:
Train trip to Seattle…advice needed!
Traveling on Amtrak train - what to expect? Share experiences.
Ehhhh, it depends. I’ve been on trains where there were outlets everywhere, and I’ve been on trains where they’re nowhere to be found. YMMV.
As for 21-hour train ride, I’ve done it. I rode from Minneapolis to White Fish about ten years ago or so, and enjoyed every minute of it. This last summer I regularly rode from Minneapolis to La Crosse in order to visit my boyfriend. I was always disappointed that I couldn’t ride further–I like sitting in the lounge car and reading my book. I make no promises about sleep, though. That was the one thing I didn’t like about the trip to White Fish. It was only about a night, though, so it wasn’t so bad.
This would be 20+ years ago, but I took almost the opposite ride, from Chicago to DC, and I enjoyed it, except when the train killed a pedestrian and we were stopped for about 4 hours while they removed bits from the suspension. And the stain on the side of the engine when we finally got off was a bit disconcerting.
But otherwise thoroughly enjoyable.
I am prone to motion sickness when reading in the car. How would reading on a train compare?
I would guess equal if not worse. Train rides feel bumpier to me than car rides.
On the other hand, I get carsick but train rides don’t bother me at all - I can read easily. Your mileage will vary.
I often ride the NYC-Chicago “Cardinal” (I only go as far as Culpeper, VA) and it has never failed to have outlets available. Sometimes, however, it only has one outlet per two seats, and sometimes it has two. The OP also said she would be going Business class. Even trains which don’t have outlets in Coach, have them in Business class.
There’s no way I could read in a car, but whenever I’m on the LIRR reading is no problem. I think for most people it’s much easier to read on a train than in a car. Cars move, turn & stop more.
Last summer, my sons and I rode Amtrak back to Dallas from their annual visit to their grandparents in Chicago. We had a very enjoyable ~21 hour trip. But we played D&D virtually the whole time, so we may not be good judges. 
My friends have told me that you can BYOB on Amtrak. So that’d be a big bonus if it’s true.