A couple more suggestions in addition to those already mentioned:
From Stechelberg in the Lauterbrunnental, hike up to Obersteinberg via the Holdrifall and Läger, continue to the Oberhornsee (good views of the Jungfrau, though not the Eiger), return via the Schmadrihütte. Could be done as a very long day (7-8 hours) or with an overnight stop at Obersteinberg (double rooms and dorms, no showers though).
On the Mürren side of the Lauterbrunnental, take the cable car up to Grütschalp, then hike up to the Lobhornhütte via the Soustal and Suld. One of the very best viewpoints to the Eiger-Mönch-Jungfrau trio, though not from close at hand.
Also on that side of the Lauterbrunnental, the hike from Mürren over the Sefinenfurgge pass and down to Griesalp has great views of the Jungfrau region.
This is an excellent guidebook in English for hikes in the Bernese Oberland:
http://www.cicerone.co.uk/product/de...---switzerland. Not sure if you will find it in Lausanne, but they sell it at Stauffacher in Bern. The Rother guide "Oberland Bernois Est" (in French) is also a good one - they have it at Payot. All the hikes mentioned so far in this thread are described in both of these books.