We were in Switzerland 8 years ago, and are making another trip there in Sept. Last time we stayed in Lauterbrunnen-good connections, etc. We visited Murren, but really didn't spend time in Wengen. I would like some opinions as to why other posters prefer one over the other. We will probably only do the easier walks, due to some present limitations. Also, I was surprised as to how many hotels are already booked. I usually book 6 months in advance.
If you checked hotel availability through booking.com and other such websites, most likely those hotels are NOT fully booked this far in advance. The websites have probably simply run out of the quota of rooms the hotel gave them. Contact the hotel directly to find out the real scoop.
We like Lauterbrunnen best because we stay for at least a week and like the central location, ability to go to either side easily, restaurants, ease of going to COOP in Interlaken, and so on. Plus we have an apartment there we love to stay in. (3rd stay there coming up on our 5th trip to the area.)
We stayed in Muerren once and it was fine for a short stay. I do think the light is better in Muerren (sunny side of the valley) and there are better restaurants than in Wengen, IMO. We always go to Wengen to ride to Mannlichen, of course.
I like both Mürren and Wengen. You saw Mürren already, so you know how very nice it is. As for Wengen, I found the shops on the main street to be more polished than those in Mürren. In my opinion, the Wengen shops have nicer jewelry, nicer souvenirs; the town has a fabulous bakery/chocolate shop. The cute gardens and chalets are uphill behind the main street. The cable car up to Männlichen starts in Wengen. The hiking trail from Männlichen to Kleine Scheidegg is about 2 1/2 miles and has many benches along the way. The cog-rail train goes from Wengen up to Allmend, then Wengernalp, then Kleine Scheidegg. Kleine Scheidegg has my favorite outdoor cafe, the Grindelwaldblick. There is a very easy walking path from Kleine Scheidegg to Wengernalp, which starts just below the rail road tracks at Kleine Scheidegg. It has a bench about half way. The Jungfraujoch train starts at Kleine Scheidegg.
There's a Co-op grocery store in both Mürren and Wengen.