In reply to alimckay:
Some of the higher rock routes in the Saas valley (which are in the Oberwallis guide) can be an effective acclimatization. Dri Hornli and Jegihorn routes all top out around 3000m. On my last visit we used these routes for exactly this purpose, makes a good contrast with Alpine snow plodding too.
On rock I enjoyed Alpendurst on Jegihorn (straightforward climbing S/HS in UK trad terms, 14 pitches) also Heimweh and Hittuleicht on the Dri Hornli (both about 6 pitches and HVSish). The best straightforward (PD) tick in the valley is the traverse of the Weissmies from the Almageller hut, the Hohlaubgrat on the Allallinhorn is good too - gets AD on here, but only one short section that needs to be pitched (VDiffish step near the summit). Have a good trip, it is a great area.