I agree with virtually everyone when they say San Fran. Chicago (the city) is reflexively Democratic and San Fran is reflexively liberal... so as long as the Dems are the liberal party... then, yeah. But, yes, the issue is the suburbs. The San Fran suburbs are filled with wealthy, educated liberals... the Chicago suburbs are very middle-working class, white ... and prone to swing to the GOP.
The elitism your party manufactures about who its voters are is truly amusing. The wealthiest people in Chicagoland are the ones who make the suburbs "GOP-friendly," SOMEWHAT offsetting the legions of poor people who make the city unwinnable.
Not necessarily.
Swaths of the near North Shore are incredibly wealthy and Democratic. Very Jewish areas plus granola types. Think Evanston, Highland Park, Deerfield, etc.
Meanwhile inland, Barrington and Wheaton area incredibly wealthy and Republican. Much more religious.
Chicago's suburbs have much more complicated voting patterns than you give off.
As for OP, SFO most likely, being the most liberal large city in the country, contested only by Seattle. It goes without saying that both are Democratic bulwarks, though.