I was extremely bored this evening, so I went looking for similar trips on European trains. I found a trip in May from Lisbon to Warsaw. Like the Chicago to Portland route on Amtrak, it's about 2000 miles and 42 hours. It has 6 transfers, including a 4 hour transfer from 10pm to 2am (ouch), and a few hours later a two hour transfer from 3am to 5am (very ouch). Only one of the trains has actual sleeping compartments. To match Amtrak I choose a private 2-bunk compartment on that train. I picked 1st class fully-refundable tickets on all 6 trains, again to match Amtrak. I've no idea if any of these trains have a dining car; I did see a photo of some vending machines. On the other hand, a ticket in a sleeper on Amtrak includes three meals a day.

The resulting price was $1067 for a one-way trip (the site couldn't find any return tickets). So even the high-priced $2000 ticket you saw doesn't seem that bad; that's the same cost as a trip of similar length in Europe.

For multi-country trips, you want a European rail pass, e.g. from this site [1].

A 5-day ticket for the entirety of Europe is about $480, though you get a 15% discount for two people. If you're only doing 4 countries, it's about $360. For $968 you get unlimited travel for a whole month.

As for sleeper cabins, prices vary depending on the route, but it's often somewhere around $20-50 per night per person [2] for a private, multi-bed "couchette".

Comparing US states to Europe is a bit like apples and oranges, though.

[1] https://www.eurail.com/en/eurail-passes/global-pass

[2] https://www.eurail.com/en/plan-your-trip/about-reservations/...

Correction: 4.5 hours, not 2.5 hours.