I just got back from a week in Ritzingen, in the Rhône valley between Fiesch and Furkapass. Finding a campsite in the Rhône valley shouldn't be too hard. We stayed here
. Don't know about chalets. There's plenty around, but of course august is high season.
There's many walking possibilities around. An easy one is to take the gondola up from Betten to Bettmeralp and the next one to Bettmerhorn. Then there's a track that follows the ridge between 2.700 and 2.900m to a saddle south of Eggishorn. You can then continue to Eggishorn, there's an easy and short via ferrata there. You can also take a gondola directly to the ferrata from Fiesch. Pictures from our trip here
(the first part is the walk I described + ferrata).
We also planned on doing the new via ferrata underneath the Tierbergli Hutte in the Urner Alps, but didn't get to it. This is a new ferrata that is accessible from the Sustenpass. According to the huttenwirt from the mentioned hut, it takes about 4hrs to do it.
I'm sure there's more ferrata's around. Enjoy the Alps!
BTW: you'll probably know this, but in German a via ferrata is called 'klettersteig'...