In reply to magicmartin:
The Leukerbad VF is the best I've done - it's a long day out and feels pretty committing - although I've always done it from the Kandersteg side biking up and down Gemmi pass to start (it would be a shorter day from the Leukerbad side).
As mentioned the Jegihorn one is also a great day out. Both that and Leukerbad finish on good summits up at 3000m or so.
A good bet could be to head into Vallais and stay at Sion or Visp or similar and then decide based on the weather - as Leukerbad and Saastal sometimes get different weather.
I've done the one in Murren and it had some nice bits, but a lot of walking through forests - at one point we were in a cow field!