Rent a car vs Swiss travel pass

Are you sure you'll save any money by renting a car in Zürich compared to just taking the train to Wengen? It sounds a bit strange to me. And Wengen is a car free town, so a car is totally useless there.

Glenn, First problem, you cannot drive to Wengen. Access by rail or hiking up the hillside only. The road ends at the valley bottom in Lauterbrunnen. Your car would be sitting in paid parking in Lauterbrunnen all the time you are in Wengen.
Search this forum or google for "Lauterbrunnen parking", there are posts about it.

Without doing the arithmetic (you have to do that yourself), it is probably better to get Berner Oberland passes while you are there, and a shorter period Swiss Pass for yourselves while you are touring. The Berner Oberland Pass gives better discounts on the mountain railways in that area.

You can buy normal tickets from Zürich airport to Wengen, and for the "Kids" back again.

Or spend your first night in Luzern, a 30CHF, 60-minute train ride from Zurich airport. Then buy the BO Pass there, and you can use it to cover the trip to Wengen.

Thank you all, and this is why its always a good idea to have other " eyes" on a problem instead of running a hamster wheel in your brain going round and round with no new ideas. I got so stuck on Swiss Train pass that yes, indeed, a car makes little sense, when I could just get tickets to and from Wengen for the "kids" and a rail pass for my husband and I since we'll go on from there once the kids have left. We'd use the B.O. pass for the Wengen time.
The idea of Luzern for the first night is interesting. Is getting to Wengen our first day too much do you think?

That depends on how far you have to travel to reach Switzerland ( how many time zones) and what time you arrive at Zurich. I see you are starting from Boston, so transiting 6 time zones. What time does your plane land?

Coming from the West coast, we have a 14-hour journey to Zurich, covering 9 time zones. We reach Zurich around 17:30 and are ready to be done traveling for the day. We like to check in to our hotel, shower and freshen up, then get outside for a walk to clear our heads. After that, a light dinner and then to bed around 9-10 pm local time. The next day we are rested and ready to continue by train to our first destination ( usually Mürren).

There are two routes from Zurich airport to Interlaken Öst, gateway to the Berner Oberland. The faster and more expensive way is via Bern. The slightly longer but more scenic route uses regional trains and goes via Luzern. Between there and Interlaken, the train follows the so-called Golden Pass route over scenic Brunig Pass and then along a lake ( Brienzersee) before arriving at Interlaken Öst. There you change to a train going to Lauterbrunnen, where you change again for the train up to Wengen.

These train changes can be a bit daunting, or at least annoying, after the long flight, so we prefer to avoid them and travel the next day. From the Zurich airport station, there are direct trains to Luzern departing once an hour. And between those, other trains with a single change at Zurich main station. Luzern is a charming town right on a lake (as is Zurich), with numerous hotel options within easy walking distance of the train station.

Thank you Badger, Chris and Lola for putting my plans back "on track" ( pun intended ). I was feeling that this trip was out of the budget but with your help I think it's doable. Luzern sounds like a perfect first day stop, with the trip to Wengen for a rested second day journey. 2 years ago we traveled independently around Germany for 2 weeks by train and it was easy, relaxing, and cost effective.
So now I'm wondering if I should look for an apartment in Wengen instead of a hotel. A new topic perhaps?