Hi We are three families traveling to Interlaken area in late July from sun-fri. We will have 9 teenagers (!) in our group and are looking for hiking, maybe canyoning, cable cars and general outdoor activities although not everyone can do super strenuous stuff. We are trying to decide both how to plan our days/activities, and if we should stay in one location for the 5 nights or split between two towns. (Wengen? Murren? Gimmelwald?) Are leaning towards Grindelwald but in reading posts are wondering if smaller villages are better (but don't know if they have access to all the activities beyond hiking?). We will probably not have cars. I can't get a good handle on how hard it is to get from place to place and whether it'd be a hassle with our big group to move around or not. Thoughts welcome and what to do and where to stay. Also, don't know what activities we need to book in advance! thanks
http://www.interlaken.ch/en/discover-interlaken.html
The Interlaken area has the reputation of being the adventure capital of the region, have a look at this site it may give you a few ideas, and i think where you decide to stay should be a traffic hub of some sort, and seeing that you plan to move around it seems it would be easier doing it from one of these kinds of places.

Switzerland has the best transport system I've ever experienced. Combined with a willingness to walk you can get anywhere so wouldn't worry about getting around, even with a group. I'd stay in one place only. You'll probably find that you want to split up and having a single place to stay makes logistics easier. You waste at least half a day in moving on, especially with a group. I'd say Interlaken, Grindelwald and Lauterbrunnen are easier and quicker to get to than Wengen, Murren or Gimmelwald, especially late at night but happy to accept alternative views on that.
I find Murren a little too sleepy when we stopped in in January. I much prefer Grindlewald for a mountain town.
I'd also recommend Ballenberg especially for the not everyone can do super strenuous stuff people. It will take all day to/from Interlaken to see it, but it's a lovely ride along Brienzersee.
Yes, Interlaken is the perfect place to do all kind of activities, especially with teenagers.
To stay in Interlaken, I suggest the Backpackers Villa Sonnenhof a great place to stay and not so expensive like the hotels there. They have also family specials. www.villa.ch/en

I strongly disagree with those who have suggested that you stay in Interlaken. Unlike all the other places mentioned Interlaken is a relatively large city with lots of big hotels and traffic. Why go to the Berner Oberland and then stay in a city?? The other options, Wengen, and especially Murren and Gimmelwald are all little towns without cars and beautiful views of the mountains. From Interlaken, the mountains are rather distant and are in fact somewhat distant which will add significantly to your travel time as you go to and from the various activities that you envision. As to which of the places to stay, I tend to think given the number of teenagers, that you will be best served by Grindelwald which is less sleepy than the others mentioned - lots of stores, things to do, but still way smaller than Interlaken. There are wonderful things to do directly from Grindelwald, (esp. First lift and hike from there, and Maennlichen and hikes from there). But it is also easy to get around from Grindelwald, probably easier than from Murren and Gimmelwald, which are in a different valley. Generally, to answer your question, it is not hard at all to get around. there are trains all the time, meaning every few minutes, or ski lifts or buses. (These are all somewhat costly though when used a lot and so you need to look into the various swiss Rail Cards - this is a must. Go the SBB website.) I should add that I really like Murren and have stayed there. But you can still visit it and I think the kids will enjoy Grindelwald more. Scenery is fabulous in both places. You can visit Interlaken if you have a cloudy day.
Interlaken is a relatively large city
MASSIVE by Swiss standards.
Population: 5,319 (Dec 31, 2008)
I do not think that many people on here did say that you stay in Interlaken itself, i did not say so myself if you though i did, indeed i recomended some sort place that is not cut off and isolated if you want to move around.
I did not mention any place in particular.
Also ENORMOUS by Swiss standards...
Grindelwald
Village in Switzerland
Grindelwald is a village and municipality in the Interlaken-Oberhasli administrative district in the canton of Bern in Switzerland. Wikipedia
Population: 3,826 (Dec 31, 2008)
And actually you did, jed. And I still think that the best view in Switzerland is from an outside table at Hooters in Interlaken on a sunny day. The Farmer Burger ain't half bad either. Just check your bill at the end. Besides the girls not seeming to know any language that anyone else uses, they tend not to be able to count ;)
Even smaller than Grindlewald is Ringgenberg, only 10mins by bus from Interlaken Ost. We lived there a while, not too inconvenient. Now we live in the massive metropolis (by Swiss standards) of Bern.