I'm with Veteran Traveler. I only upgraded to 1st class once, and that was a 5 hour train ride, and the upgrade fee was nominal. And there are quite a few trains where you can make seat reservations in 2nd class. I only make them on trains I know will be crowded, but it can be done.
1st class is a little nicer and the seats are a little better, so if that matters, go for it. But for almost $50 to upgrade 4 people, it wouldn't be worth it to me on a 2 1/2 hour train ride. That's me, though. I usually don't spend a lot of extra money on fancy hotels, either. 😊