A friend just asked about relocating here with a family. I wrote him, in part:
Zurich (and Basel) are full of english-speakers. In many workplaces it is entirely possible to live in an English-speaking bubble. As I say, international school can be expensive. It is also a very particular world -- very upper-middle class/international executive oriented, with the attendant values and their positives and negatives -- creative/dynamic curriculum and teaching styles, lots of bright and articulate kids, competitiveness, workaholic attitudes, ambition, open-mindedness (along certain axes), drivenness, etc. It is a bit of an artificial world in certain regards; if you only speak English there is lots to do and it can be quite fun, but you are separated in a way from the deeper life of the city. Maybe less so in Zurich; there are really a LOT of English-speakers in Zurich.
It would also be possible to send your kids to Swiss public school; the schools are very good, and open to foreigners, and they are good at crash courses in German -- they absorb a lot of foreigners -- and kids learn languages much easier than grownups. If you send your kids to international school and they hang out in English-speaking playgroups and so on, they will probably not learn that much German; after a year in the Swiss public schools they will likely be fluent. It might be a hard year though; adapting to a new language compounds the difficulties of adapting to a new culture. Kids in the international school world are adapted to transience and expect everyone and everything to be new every few years; all friends they make they assume will turn into penpals at some point. Not so kids in the public schools. There are thus pros and cons.
On a day to day level it is easy to get by in English; the Swiss speak it pretty well, though not at Scandinavian levels. But there is no problem buying train tickets, shopping, going to movies, etc., entirely in English. And in Zurich particularly it is easy to find English-speaking friends and playmates. If you go the international-school route the playmates are likely to be more widely distributed, which can mean playdates and transportation hassles; if the immersion route, it's more likely that they'll make friends next door, which means "bye mom, I'm going to Ueli's, be back at dinner."
Swiss culture is very different than US culture; in some respects very freeing, in other respects suffocating. In Zurich you have the population density of downtown DC with the crime rate of White Sulphur Springs. This means freedom for kids: we have no worries when Aviva rides the tram across town alone. On the other hand, everything is closed on Sunday and at night, it is often a nightmare scheduling to use the washing machine in the apartment complex basement, etc. Americans are used to 24-hour-a-day convenience: in Switzerland, the individual adjusts themselves to the community's needs, not the other way around. It's a little like Japan, from what I hear of Japan.
The Swiss are shy. People on the tram never speak or make eye contact. You can live next to people for years and interact only within rigid boundaries of propriety. On the other hand, often they are grateful when you break through these barriers and make contact.
In many ways, moving from the US to Switzerland is like moving from Mexico to the US. You find yourself thinking "so this is what an actual first-world country looks like." You find yourself sometimes relieved to have left the brutality and corruption and glaring inequities and disorder and Kafkaesque bureaucratic hassles and bad urban planning of your homeland behind, but you also find yourself missing its warmth, its joy in life, its social freedoms and communities, and your role there. This is all, of course, more true if you are doing the immersion thing than if you are in the American expat bubble, but it is somewhat true regardless.
After initial hassles (getting your wifi to work, etc.), expect the first three months to find everything charming and delightfully quaint or exotic, and to chortle about the wacky differences between home and Switzerland. Months 4 through 18, expect to be constantly aggravated by differences which have lost their novelty amusement value and are now just a fucking pain in the ass, and to spend your trips home gorging on burritos, bagels, and sushi. After that it levels out and you will have reached some accomodation with Switzerland, and authored a new identity for yourself there.