Agreed, that would be awesome!
I'm originally from the Bay Area, and when they first showed us the map for the game, I actually laid out how much of the Bay it appears to cover.
My hometown is San Mateo, which sadly it skimps out on almost entirely. I would definitely love to see better representation from that.
The only hope would be if San Fierro makes a triumphant return to the GTA series, but anyone who doesn't live here seems to think that it's San Francisco and then just a bunch of farm towns all over, lol.