We spent a bit over 2 weeks in Switzerland. Here’s a brief overview of where we want, and what we enjoyed.
Beautiful town. Both the “old” and “new” cities are gorgeous. Visit in the summer, so you can go swimming in the Aare river (probably 3 days in that case). The cafe in the Rose Garden is excellent, as is the COPAIN bakery - best sourdough I’ve ever had!!
Over the course of 4 days, we hiked from Kandersteg, to Blüemlisalphütte, to Gspaltenhornhütte, to Rotstockhütte, to Mürren:

It was absolutely insanely gorgeous, and also incredibly difficult. The static pic doesn’t fully convey how steep the hikes were. Check out the full writeup for all the details!
Wengen was a phenomenal place to stay. We stayed at the Grand Hotel Belvedere, which was so nice it has changed my expectations for hotels in the future. The food was excellent; the sauna, steam room, and pool were unreasonably beautiful; the room was stunning; the view was unreal I mean the whole experience was just fantastic.

In my opinion, if you can stay in Wengen, at a hotel that has a view of Lauterbrunnen valley, you get the best of all worlds. It’s easy to get to a ton of other places (Männlichen via gondola, Lauterbrunnen via train and therefore Interlaken, Grindelwald, and Mürren); the view is unbeatable (mountain view AND valley view), and the town of Wengen itself is very pleasant (no cars!). Plus, the train ride down to Lauterbrunnen gets you the BEST view of Lauterbrunnen. I really think Wengen is ideal.
Wengen also has a laundromat. It’s pretty wacky to use - the guy who runs it is extremely cranky. Just accept in your heart that he’s a character, and enjoy the experience. If you’re polite to him, he’ll take your clothes to the “real” hotel dryer, and they’ll be done in 5 minutes. We hung our wool up on the balcony, so it wouldn’t shrink.

I found it tough to figure out how to plan the Wengen area visit, because it’s so 3D and I just couldn’t wrap my head around it. The map below might help, and also try playing around with Google Maps in 3D mode.
SUPER fun. Super bananas gondola to get up there, then there’s a spectacular view, and a super fun rotating restaurant. Definitely recommend. The ticket for this was included in our Berner Oberland pass, which made it a no-brainer.

We found out that you can tour constructions sites! We’ll definitely do that if you go back. Evidently this excavator pushed itself up the mountain, backwards. Wish we could have seen it, and learned more about Swiss engineering!

We spent a day here, swimming on the beach near the Neuhaus swimming steps. It was unbelievably beautiful - one of my favourite days of our trip. Definitely recommend a lake visit on a hot day. The water is bone-chillingly cold, and it feels fantastic. Take some time to also ride the ferry. The lakes are enormous, and the ferry gives you a super fun view of the cute litle houses along the banks.
We didn’t spend any time in Interlaken, but it looks quite busy and slightly crowded, with minimal views of the mountains.
We got a bit unlucky in Zermatt - it was cloudy and rainy for the first 3 days, and my husband had Covid. So, we maybe didn’t have the absolute best possible time. BUT, we got super lucky on the last day, and not only did it snow in the morning (!) but it was perfectly clear and sunny after breakfast (!!) and we got a stunning view of the actual Matterhorn.

