Definitely take some time to meander through Golden Gate Park, maybe in conjunction with a visit to one of the many good Sunset/Richmond Asian restaurants. It's my favorite place no matter what the weather is. I especially recommend the Botanical Gardens, which always have interesting plants even in January! Plus it's free. Great place to jog. And the DeYoung Museum is right there, too.

Also, if you've never done it before, walk or ride a bike across the Golden Gate Bridge. Great views and good exercise, too!

I'll leave the restaurant recommendations to the foodies.