If SpaceX were to put a Starbase / Starport in the SF Bay Area, where would those be? Santa Cruz and/or SF?
I don't think you can launch from the coast around San Francisco. You want to launch away from the coast so that if anything goes wrong, you don't drop a fueled Starship onto a populated area. Vandenberg stays 30 degrees away from the coast south of it. Because the coastline in the San Francisco area is at about 157 degrees of azimuth (NW to SE), to keep that 30 degree angle of safety, you end up launching south or even a little west, which means that you'd lose over 300 m/s of velocity and have a hard time getting into the more commonly-used orbits. For example, I know of no launches from Vandenberg that have gone to the ISS.
You could move the launch off the coast onto an offshore platform, but my math says it would have to be 135 miles out to keep the appropriate safety margins, but you would get a nice launch azimuth as eastward as perhaps 125 degrees.
Oh, and because I found the numbers, Vandenberg's launch azimuth limits are 201 to 158 degrees, while Cape Canaveral's are 35 to 120 degrees.
Note that launch azimuths are compass directions from the point of launch. In contrast, orbital inclinations are relative to the equatorial plane. So a launch azimuth of 53 degrees doesn't get you a 53 degree orbital inclination unless you launch from the equator. You have to factor in your latitude to convert between launch azimuths and orbital inclinations. And even then, a rocket can maneuver during the launch to change the orbital inclination (a 'dogleg' maneuver).
Edit: I missed it in the image, but it seems to say that the safety factor is about 18 degrees (coast at an azimuth of 140 and maximum eastern launch azimuth of 158 degrees). That throws off my numbers. Your best launch azimuth becomes 157+18 degrees = 175 degrees, which is doable, but not usable for ISS missions and such.
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