Area in Switzerland that is similar to Wengen

I loved Kandersteg and Oeschinensee hike, and Fruitigen.

And you can hike the completely different area known as the Loetschental, isolated from much of the world until the '60's.

Bettmeralp is another car free village in the Valais with lots of hiking on the other side of the Aletsch Glacier. Highly recommend!

I did not mention Bettmeralp as it is not within the BernerOberland Pass area. Plus I like to keep it out of the spotlight.

Kandersteg is nice and offers good hiking opportunities in the area, in the adjacent Gasterntal, as well as the remote Lötschental. Oeschinensee is beautiful. But some of the hiking trails above there have been closed due to the threat of rockfall from the Spitzerstein.

https://www.swissinfo.ch/eng/sci-tech/cop26-slpine-climate-threats-living-in-the-shadow-of-the-spitzer-stein-mountain-switzerland/47011992

https://www.gemeindekandersteg.ch/spitze-stei

Also, Kandersteg is home to an International Scouting Center, and the town hosts hundreds of Boy Scouts and Guides. It is great to see all these kids from all over the world learning to enjoy the mountains, but I would not call the village particularly “quiet”.

https://www.kisc.ch/why-kisc

It is a great place to visit and hike.

If you aren't committed to the second base being in Berner Oberland, consider Ticino, the Italian-speaking region of Switzerland. We just wrapped up a week there and were amazed at the great hiking -- roaring blue rivers, great waterfalls, atmospheric villages. Our method was to use the Postbus system to ride to the upper end of a valley and work our way down. We enjoyed the Onsernone Valley (the most rugged); Verzasca Valley (most beautiful but also the most popular); and Vallemaggia (the most food-oriented). There are still others we didn't get to. You might have your heart set on staying in the BO, which I would understand. But we weren't expecting to be so blown away by the hiking in Ticino, and it might make an interesting contrast to your other experiences. My trip report is here.

If that isn't of interest, I'd second (or third) Kandersteg, and also throw out Saanen as another possibility for pure Swiss village charm.

Thank you for your responses! Is there another mountain area outside of the OB area to the east that is really nice?

To the east, Pontresina is very nice. We have been twice for a week each time and will probably go back in 2025. We go in autumn so not sure about summer crowds.

The Engadine Valley is to the east—-Pontresina, glitzy St.Moritz, and some smaller villages. It is known as a hiker’s paradise, but we have yet to spend time there.

https://www.engadin.ch/en/

https://www.myswitzerland.com/en-us/destinations/engadin-st-moritz/

Pontressina is a great area, and you could ride the Bernina Express regional trains down to Tirano, and back. We did that post- covid, and the scenery is so spectacular , I enjoyed the way back as much as the way out, about four hours RT.
Enjoy!