Figure out the major muni train or bus stop I'm trying to get to, and then either walk to it or walk to a shared bike dock and bike to it. Same thing on the other side, if necessary. Often I just bike the whole way to get some exercise and see the city: "it's about the journey, not the destination", right?
The hills make it less walkable than other cities, but if you are healthy you should get used to the hills pretty quickly. I loved walking back to Nob Hill or biking back to NoPa after work. The hills are daunting at first. Sometimes you'd need to get off your bike and walk up parts. But once you get used to it it's not a huge issue.
The cool weather also helps cooling down after you get to your destination. Compare that to somewhere like Austin, TX, where you start sweating the minute you get out of the AC and into the year-round humid weather...