As someone who faced a similar decision two years ago (whether to go to MSRA or Google in SV for my sabbatical), the air pollution was one of the top three factors. I'd love to spend a year in Beijing, and the food is a bonus. But we decided it wouldn't be appropriate or fun to have a 3 year old inhaling that for 365 days. This was from experience - we speak to a week when she was two, and she'd have a coughing spell every time we left the hotel. But yes - many stresses. Family, not speaking the language very well, etc. In the case of seanmcdirmid, though, he's fluent and seems to like the food. :-). (welcome back, btw)