One thing to know about these rail passes is that you can usually upgrade them wholesale to first class, or just by a first class supplement for particular legs of the journey. I did this for a trip from Basel to Biel to take a ride on the lakes there. It turned out to be cheaper to only get a first class upgrade on the train ride, as the boat was 2nd class only.

To upgrade these passes, just grab a seat in first class and wait for the conductor to check your ticket and ask him if you can upgrade.