Help with 3 days in Jungfrau-Wengen or Lauterbrunnen or ?

We loved being up in mountains in Grindelwald and also liked Murren and Wengen when we visited them. We chose Grindelwald because we have a car there which worked out well. We visited Lauterbrunnen too and it was the only place we didn’t care for. It was down in a valley rather than up high with sweeping views like the others I listed.

I would stay at the Hotel Bellevue in Wengen for great views of the Lauterbrunnen Valley and very nice rooms and take the train to Lugano.

I also liked being up in the mountains, chose Murren. It's a view you never forget. We completely splurged on the accommodation more than I ever had in my life, but it was a special occasion. I would start looking at accommodations in all and see what appeals to you. I booked sort of last minute and later in the season, so it was somewhat limited. I would book very early once you see what you like at a budget you like.
The transport is really easy.

Definitely stay in a car free village - it’s one of the really unique parts of Switzerland and a special experience. There are a few more hotels/restaurants/shops in Wengen, it’s a bit simpler to connect to, has valley/mountain views & is busier because it’s a hub to get to the Jungfraujoch while Murren is more historic, is quieter, has more dramatic mountain views & has more hiking directly from there vs Wengen. You really can’t go wrong with either. We live in Murren for the summer every year so I’m slightly biased towards it, but we’ve stayed in Wengen twice and enjoyed it as well.

For hiking, look into the North Face hike counterclockwise from the Allmendhubel (Murren) & the walk from Männlichen to Kleine Scheidegg (above Wengen).

It takes a little time, but it’s very easy to get from one side of the valley to the other. So, you can stay in Wengen and still do a hike/explore the Mürren side and vice versa.

Murren is one of the best places we've been for sheer beauty and serenity. The views from there are spectacular. Strongly suggest doing the North Face Trail. It's not a strenuous hike: really more of a walk that a hike. Take a picnic lunch and enjoy the day. Since this is your honeymoon, may you love long and prosper.

Thank you everyone. It seems like Murren or Wengen are the favorites. I will see what kind of accommodations are available. Please feel free to comment more if you have anything to recommend-thanks!

If you are going to Lugano afterwards you may want to go to the Jungfrau Area first, and then to Luzern. Assuming you land in Zurich (and leave again later from somewhere in Italy) you could do ZRH - Wengen o Murren - Luzern - Lugano - Milano - ....

Sounds lovely--If you go with Murren, I would do a hike one day (they can advise you at the Sportschalet, but there are tons of options) and the other day, head up to Schilthorn (check skycam first thing in morning) and down to Lauterbrunnen to see the waterfalls (if you don't do that on the way in or out, which would be easy as well). The hotels in Murren serve good food--we ate at Alpenruh and Edelweis. There is a well regarded Chinese restaurant and I was crushed that it was closed when we were there (October).
You might want to share your overall itinerary, because you might get some tips to save a day or two here or there.

I am a big fan of Lauterbrunnen as a central location but the peacefulness of Mürren or Wengen would be nice on your honeymoon first trip here. (You will be back!) Mid-Sept is still very busy in the area and the large groups at the train station in Lauterbrunnen are overwhelming at times. I would pick Wengen in your shoes, as the easiest to reach on arrival with luggage. There are lovely walks there that you can do without leaving the village or taking a lift, and the Männlichen to Kleine Scheidegg hike is not to be missed, an easy half-day from Wengen.