I am Senior SWE at an Alphabet company. Came to MTV in middle of 2015 from a company in the midwest where I made over $200K last year (much of this was profit-sharing bonus), and I was definitely at top of the market for my city.
My total compensation for this coming year (based on current value of GOOG, obviously this can vary) is projected in the mid-$300Ks. (Some of this is initial GSUs vesting, so it's slightly inflated). With the difference in cost-of-living it should be about equivalent to where I was last year. Too soon for first refresh grant, so I can't speculate about where it may go from there.
I've already gotten a larger raise and bonus than I expected, seeing as I negotiated a better offer than they originally gave me. My manager has been talking with me about what I need to do to get to promoted Staff level.
So yes, there is money to be made in SV, at big companies.