I see there is a substantial cost difference between the 1st and 2nd class Swiss Travel Pass (about 50% more). For off-peak travel, is the first class option worth it?
Standard class (2nd class) is perfectly fine on Swiss trains. The minor differences in the two classes of carriages doesn’t really justify the significant price difference in the train tickets or the Swiss Travel Passes.
There are fewer seats in 1st class carriages. Seats are 3 per row as opposed to 4 per row in 2nd class, as well as a bit more seat pitch. That is pretty much the reason for the price difference. As was said, 2nd class is perfectly comfortable, and gets you there at exactly the same speed.
Really a good deal with 1st class with Berner Oberland pass with train seats and access to top level on cruises on Lake Thur and Brienz.
Remember, you can always buy an upgrade ticket on any given train or boat, which is basically the price difference between a 1st and 2nd class ticket. You can do this on a case by case basis as you feel the need or desire.
Keep in mind that there are no first or second classes on gondolas, so if you’ll be using a lot of those, first class is a waste. We traveled in 2nd class in peak summer with no problem. Always plenty of seats.