This is great---thanks everyone!
Brooke--long skirts aren't their style either; they are both very athletic (tennis, running, yoga) and like to dress accordingly. They won't be wearing shorts, but will have bare arms and shoulders (except when we cover up to visit a church). And we'll be at the beach or pool in a couple of places. Fortunately they are very compliant about sunscreen use, and were fine even in Hawaii.
Nigel---that Migros brand is a great suggestion. There is a Migros in the Zürich Hauptbahnhof, and I need to go there anyway to pick up my favorite Swiss toothpaste and some other products I like.
Pat---Ombrelle is the one I was thinking of. I'd like to try it. None of us have any particular sensitivities, but I'm always looking for good sunscreen options.
If we buy extra and want to bring it home, I won't mind checking one bag for the return flights. It's mainly for the outbound flight we want to carry on. If they misplace one bag on the return it's not a big deal.