Which rail pass to choose for a couple

Hello Pathar, and welcome! I think a 4 day Swiss Saver Flexi Pass would be a good options, using free travel days for your long trips on February 4, 5, 7 and 8 and profiting from 50% discount on February 6. The Swiss Saver Flexi Pass's validity would end by February 8, but that's no problem since you only want to do some local trips within Geneva on February 9. If you plan an overnight stay in a hotel in Geneva, you'll even receive a free Geneva Transport Card providing unlimited use of public transport in the city.

None of the Swiss rail passes would cover the trip from Geneva to Lyon, as they're only valid within Switzerland. Eurail Passes would be valid, but they would be too expensive if you only need the trip Geneva-Lyon in France. If that's the case, you're better off buying regular train tickets for that trip.

Boat trips on lake Thun can't be made in February (they'll start again in April).

Hello Pathar. Yes, between Wengen or Grindelwald and Kleine Scheidegg you have to pay 75% of the normal fare with a Swiss Saver Flexi Pass. Regular fares can be found by entering your trip in the Swiss timetable or at the Jungfrau railways website. The Zermatt-Wengen and Grindelwald-Spiez will be for free this day.