I plan to move to SF in the following months, but this is one of the issues why I think that I won't stay there permanently, but will move back to Europe after a few years.
In my experience, big companies in the U.S. are often willing to negotiate on the number of vacation days issued. I negotiated 4 weeks of vacation/sick time + 6 holiday days at my last job. I took a a couple thousand dollars less than my target salary, but I was definitely happier.
Also, banks, educational institutions, and government offices are more generous when it comes to vacation days. Tech companies and ad agencies are generally the stingiest.
I plan to move to SF in the following months, but this is one of the issues why I think that I won't stay there permanently, but will move back to Europe after a few years.