When using the train system in Poland, is there an advantage to traveling first class to justify paying the additional money?
I think either one will be very inexpensive by Western European standards, so if you're a little risk-averse pick 1st class (I think the difference in pricing isn't that great either). I don't recall which one I used unfortunately.
This is your chance to go first class in a less expensive way. Its worth it. Second class is just a cut above cattle car.
First class cost 50% more than second class but even then it's still not expensive by western European standard. I had different experience than Monte. Second class was OK for me. Long distance trains have usually compartments. Second class compartment usually sits 8 people, first class 6. But in some special expresses (like Eurocity, Intercity) even second class has just 6 seats per compartment.
Second class was fine for me. I didn't try first class in Poland. If you are going a long way, it might be worth going first.
We recently came back from spending a few weeks in Poland and took some train rides. Here are a few examples: Torun to Lublin, 5h25m ride: paid 98zl/person ($30) for 1st class, second class would have cost 65zl ($20). Lublin to Krakow, 5h ride: paid 96zl/person ($29.50) for 1st class, second class would have cost 62zl ($19). Krakow to Warsaw, 3h ride: paid 60zl/person ($18.50) for 2nd class, 1st class would have cost 93zl ($29). The long and short of it was we gladly paid an extra $10 each to sit in first class on a couple of the longer legs, because, as Ilja already mentioned, there are only 6 seats in those compartments (3 on each side facing each other). The seats are wider and there is more room to spread out, plus we found the 1st class car in general to be quieter and not very busy. It was a lot more conducive to napping. From Krakow to Warsaw we sat in 2nd class but lucked out, as our compartment only had 6 people in it out of a possible 8. If all 8 had been in there it would have been kind of claustrophobic to me but it was only a 3 hour trip. In short, it may not seem like a big deal but really, it was a lot more comfortable in a 6-person compartment, especially if it's a long leg (to parrot what everyone else said). And hey, where else will it only cost you $10 to ride in 1st?!
For Krakow to Warsaw and Warsaw to Berlin, I was satisfied with 2nd class. I was not in a compartment on either train. I was just in an open seating area.
Thank you for all your feedback. We have purchased our tickets and are looking forward to our upcoming trip.