The Bernese Oberland: Lauterbrunnen's valley, and the Jungfraujoch question

The Lauterbrunnen valley, with Mürren and Wengen on its cliffs, is the Switzerland of the postcards, and most of it is free: walk the valley floor past Staubbach falls, ride up to Mürren, and hike the ridge paths with views of the Eiger. The Jungfraujoch train is spectacular and very expensive; on a cloudy day it's a tunnel to a white-out, so check the live webcam before you commit. Grindelwald First and Schynige Platte are cheaper and often clearer.