In reply to jezzah:
If you want to bumble around at 3000m take the cablecar/train from Lauterbrunnen to Murren (~30 mins). From there you can walk up to 3000m at Piz Gloria which has a nice revolving restaurant and James Bond Museum. Quite a tiring walk btw, 1,200m elevation and it hits you if you're coming in from sea level or not 100% fit. The via ferrata at 1800m in Murren is a good one if you like that sort of thing.
The other cracking walk in the area is from Stechelberg to Obersteinberg. Stechelberg is a short bus ride from Lauterbrunnen. 1000m gain to Obersteinberg, which is an off grid hotel at 1800m.
If your objectives are Oberland 4000m peaks, you could consider walking to the Konkordiahutte instead? Amazing location, nice hut (nicer than Monchjochhutte) and you can do the Grunegghorn / Grunhorn which is nearby. There is some sport climbing behind the hut.
Be aware that the conditions on the Jungfrau have changed since Les Swindin's book was published and you need to be a little careful now on the saddle section (you probably know this). Definitely worth starting from the Monchsjochhutte to get an early start - by the time we got down to the bottom we saw people still coming off the train and getting started during the heat of late morning, which is completely mad. Particularly as a couple of days later a whole section fell down at around 1400.