Cost of living is higher and the increase pay doesn't always make up for it...but also keep in mind the non-tangibles. If you move to one of those areas, you're going to surround by some of the top tech talent in the country. That means you're learning, collaborating, competing, and socializing with some of the best peers you could have anywhere. That has a lot of career advantages...mobility, huge potential for upside, exchange of ideas, etc. It also boosts the standards of local universities, schools, etc.