In reply to liberation: There is also a small campsite behind the Bergheimat Hotel in Saas Grund, the bonus of this one is use of the Hotel's indoor pool (well appreciated after a couple of hill days). It is very close to the Saas Grund lift too, but rather boxed in by chalet hotels.
I've heard that uplift in the valley is free this summer in an attempt to boost visitor numbers, if true that could save you a packet.
Helps to have some German or a phrasebook for the Hohsaas and Weissmies huts as the Guardians do not speak English (although other staff at these huts do), the Almageller hut Guardian has good English.
If you fancy the bolted climbing on the Dri Hornli you should be able to pick up a colour topo leaflet in the Almageller Hut (was 3Chf in 2010), the multi pitch lines we did there were brilliant.