Jul 20, 2016 - 10:56 PM
As the others have already said, the Jungfraujoch is the big attraction in the Oberland. It is very expensive, however. For a family of 4 it will cost several hundred dollars. (Check for special deals. You may be able to get a family discount).
The Trummellbach falls are a lot of fun. Take the bus there then funicular railway that goes through a tunnel to near the top, then walk back down through a series of tunnels that follow the waterway. Quite intense!
The Schilthorn cable car is just up the road. It's one of the scariest I've ever been on. For the full effect, try and stand at the front window. The kids will love it! The view from the top is magnificent, but apart from the restaurent, there's not much to do apart from take pictures, and again it's not cheap.
More leisurely and more scenic would be taking the train to Kleine Scheidegg and walking up to Maennlichen where you get a fantastic view of the Lauterbrunnen valley, then taking the cable car down to Wengen before walking (or taking the train) back to Lauterbrunnen.
It's a shame you only have 1 day to spend there, there's so much to do. Have a fantastic time