I moved from the Bay Area (lived there 2 years) to Seattle (well, Bellevue) a few years ago. I had two elementary schoolers and a toddler. The main reason was that although I was paid fairly well, we would never be able to buy a house. So every year was a race between my raise and rent increases. We lived in a pretty decent school district, but it was difficult to move with in the same district, let alone the same school. I was looking at my oldest entering middle school and I didn't want her to have to face the prospect of changing schools every 1-2 years.
Our situation in California let us offer everything except stability. Younger kids are fine anywhere as long as their parents are involved, but older kids benefit from social stability so they have time and space to define who they are.