Help planning Switzerland 3 day itinerary

Wow, that is scary fast. I think you and your kids would like Lauterbruen valley best. The waterfall in the mountain is very stunning for any age. J

3 nights just do Lucern. there are plenty of day trips great mountain excursions close by there and it is only 1 hour from the Zurich airport. Also there Is Lake Lucerne you can take a boat that connects you to the cogwheel train up to Mt. Rigi. It's beautiful up there. The Lauterbrunnen Valley area is too far for just 3days

For a noontime flight home from Zurich there’s no need to be there the night before your flight. In Switzerland, the trains run exactly on time, and Zurich is 2 hours 27 minutes by train from Lauterbrunnen. The airport is 12 minutes by train from downtown Zurich. So, give yourselves 3 nights wherever it is that you choose to go. I agree with Joanne in recommending Lauterbrunnen as the place to base yourselves for your 3 nights. You’ll have quick access to Muerren, Gimmelwald, the waterfalls of the valley and hiking the easy trails above Wengen for views of the Jungfrau, Munch and Eiger mountain peaks.

Since I've been to those same places with my own teens, here's what I would do:
Drive to Lucerne for a brief visit to the Dying Lion monument and then right next door to the mirror maze at Gletschergarten, https://gletschergarten.ch/en/adventure/mirror_maze

Grab a bite in Lucerne, then drive to Lauterbrunnen. If you can now reserve a trailer or bungalow at https://www.campingjungfrau.swiss/ that would be good. Otherwise see what you can find via booking.com.
To see what to do in the Lauterbrunnen region, check out https://lauterbrunnenhiking.wordpress.com/

is this a road trip with car right after a transatlantic flight? The 6 am arrival in Zürich sounds like a red-eye to me.

Thing is, the train station is right in the airport and you can get to Luzern or Lauterbrunnen way way faster than with a car, and no having to get the car.

Everything in Luzern is walking distance and parking is eye-wateringly expensive. In the mountains of the Lauterbrunnen Valley you can't have a car anyway - you'll use the cogwheel trains and cable cars to go everywhere and you'll be paying for more parking.

I know that with 4 it sounds better in the car, but is it?

And for the unfortunate driver of the rental car, a lot of the Swiss scenery will be missed because the driver will need to pay attention to the road rather than enjoy the scenery. Traveling by train solves that problem.