It's not cheap, but I have an acquaintance who got a Bahncard 100 with 1st class access because she works at the Bahn and it sounds quite life changing. ICEs on major routes are somewhat frequent and you can just get on the train without reservations or anything. Wanna go from Hamburg to Berlin for the day? You pretty much just walk to the train station and 2-2.5 hours later are in Berlin. You can do stuff on the train. Read a book, watch a movie, start work on your new startup's app or get a currywurst from the restaurant car. I am quite jealous of this.