Do we need Swiss francs if ski-ing over from France?

Well, they would take Euros in most shops and restaurants in Swiss resorts but at a very unfavourable rate. I think it's about 1:1 at the moment. There can be some restrictions on credit card use (like a minimum purchase) in mountain resaurants and you may not be able to pay with it for a couple of hot chocolates. But you won't lose much on excahnge rate with a small purchase like that if you pay in euros. Just make sure you have small notes - 5 or 10 euros, because you'll be given change in Swiss francs. And no euro coins too. Usually only notes are accepted. They are clever over here - no surprise that in traditional Swiss restaurants you pay but often end up making your own food:)