You can take the train to Portland from Norfolk via WDC & Chicago, just over $300, just over 3 days.
A lot more comfortable, a lot more food choices, a lot more space on board, a lot less stops, a lot more time to read and relax, a lot better departure and arrival times (9 am - 10 am +3 days).
Pretty much all of the long-distance passenger train routes in the US are run by Amtrak, which is a “quasi-public corporation,” and is owned by the federal government. The goverment formed Amtrak in the early 1970s to save the intercity passenger train industry, as the private railroads (which had, until then, been running the intercity passenger train system) were losing large amounts of money from it (largely due to competition from cars and airlines), and wanted out of the business.
In the “Northwest Corridor” (running from Washington, DC, through Philadelphia and New York City, to Boston), Amtrak owns its own tracks, and is pretty popular (and relatively reliable). Amtrak’s long-distance trains, on the other hand, largely operate on tracks owned by the private railroads, and frequently run into delays due to interference from freight trains.
So, for long distance travel, it’s slow, and often expensive.
/hijack
Back to the OP: I haven’t ridden on Greyhound since the '80s, but my sister had ridden it several times in the past few years. She relates stories about delays and fellow passengers with serious hygiene issues, and wouldn’t ride on the bus again unless she had no other option.
Northeast corridor 
And you’ve got a lot more room to get up and walk around on the train compared to a bus. You can go hang out in the observation car if you get tired of sitting in your seat. You have the opportunity to eat meals in the dining car as opposed to grabbing some fast food whenever the bus stops long enough to do so.
The last time I was on a long distance Amtrak train, around 2015, the train did not have wifi. Unless they’ve changed it since then that is one negative compared to Greyhound. You might be able to use cellular data some of the time, but I wouldn’t count having cell service in some of the areas the train passes through.
That was probably an Acela ticket - they are way more expensive than the regular Amtrak coach ticket. But the NJ Transit is definitely cheaper. When I lived outside Philly it was maybe a 10 minute longer drive to get to the Hamilton, NJ transit station than to 30th Street Station. Plus parking at Hamilton was way cheaper and easier than 30th Street.
But is is slower, kind of like taking an S-Bahn vs. an IC train in Europe.
Amtrak? I do not know about lately, but they used to have a 23 hour layover in SLC going from Denver to Portland Ore. At least ask about it. Other than that it is OK I am told.
Greyhound? I would not recommend it.
As I understand it, the new buses go to the “Northeast corridor” & the junk that the new buses replace gets moved to “The West”.
They do not get rebuilt, nor refurbished. They just get thrown onto service as is. Also IME, the maintenance is marginal at best. It is not unusual for me to see Greyhound buses broke down along side the freeway & in the depots, or in the roadside park & rides.
I have heard from hitchhikers that were former bus riders that Greyhound will eventually send another bus to get the passengers to their destination. At least partly due to the largeness of this part of the country, it can take over 6 hours for a replacement bus to arrive. Then the replacement bus is often the one that is out of service due to it having quite a few “maintenance issues”, not good.
One couple I gave a lift to had been transferred to a different bus six times between Bakersfield Ca. & GJ CO. due to bus breakdowns.
God forbid that it snows that day. If it does, well, good luck! Most of the drivers have no idea as to how to install tire chains. AMHIK! Heck, IME, many of the drivers have never driven in the snow, & they are driving buses across Colorado???
Then Greyhound has to look at the drivers being tied to an hourly limit on their driving. If the bus is broke down, they are still “on duty” & those hours count against their driving time. IMHO this is a good thing, but it does affect the service out here.
So to repeat, No, Oh Hell No, do not take Greyhound across the USA, especially in the winter time.
Of course it is a free country & you get to decide. Yet, you did ask for advice. This is mine.
IHTH, 48.
:smack: I knew that, too.
I think “travel centers” is correct. We noticed two or three Pilot Travel Centers while driving up to Oregon when we moved.
Last year, a childhood friend was in the region and came to my city, 150 miles from our hometown, to attend a family reunion (and she bunked with me in the meantime; it was wonderful to see her). She said the bus was clean, and the station definitely was spotless, but the most disturbing thing on the 5-hour ride, due to a couple of stops, was the really wasted woman with a dirty little boy, to whom my friend gave her lunch because she could tell he was starving.
She had considered renting a car but decided to take the bus because she’s not familiar with my city, and said she’s really bad with directions, even if she had a GPS.
[AD - 1 of 1]
(Cue jaunty music)
Relaxin’ while we’re ridin’ in a Greyhound bus!
We’re seein’ all the scenery and comfort plus!
It’s such a com–fort to take the bus,
And leave the drivin’ to us!
In a Greyhound bus, lucky us, in a Greyhound bus!
[/AD]