1) If time permits, you might consider walking a block south from 866 Valencia (Borderlands) to 826 Valencia. It's a non-profit educational organization co-founded by Dave Eggers (A Heartbreaking Work of Staggering Genius) that provides classes and programs that help kids develop their writing skills.
It's also the best pirate supply store on the West Coast (click the ship on the lower right part of their home page) - they offer designer eyepatches, peg-leg sizing charts, bottles of "Captain Blackbeard's Beard Dye (Black)", mermaid repellant, etc.
2) The San Francisco Giants baseball club is playing in town from August 1st to the 10th. This is most likely irrelevant to your interests (although their ballpark is quite lovely and the onsite pub has cask ales), but depending on the time of day and the direction you're heading, the various flavors of mass transit (MUNI, BART and Caltrain) may be filled with polite, cheerful, orange-and-black clad citizens to the point of Tokyo-subway level compression. Caveat vector, and try not to make eye contact with anyone wearing a fake beard and/or panda hat. Especially the young'uns.
]]>Then, last year at a library sale I picked up a book written by a local newspaper journalist who reminisced about his days on the city politics beat from the 1940s to the 80s. In one chapter he took great pains to describe what it was like to actually work in such a building. The place roasted in the summer and froze in the winter, the center corridors visibly sagged from true by one or two feet, the plumbing tended to regurgitate from time to time, the city jail was located just below the municipal courtroom (and its occupants could be heard through the paper-thin interior walls adding their contributions to case law), and during the rainy season the offices in the lower levels ended up in the same condition as the bilges on a ship (i.e., ankle-deep in water). He closed by wishing they had replaced it earlier, and I found myself unable to muster any sort of counterargument.
So what I'm trying to say is...um, yeah. "Old" != "necessarily worth preserving".