Depends where in San Francisco. A lot of business travelers in particular perceptions of SF are probably colored by the areas near the Moscone (and Fishermans Wharf). Though most of SF is relatively sane in general--certainly not like the Times Square area in NYC.
> Times Square area in NYC.
quick funny story, my family and i were in Times Square last year for New Year's. Thousands of people everywhere as you can imagine. We're walking down the sidewalk and right as rain my wife runs into someone she knows from all the way back in Texas. Among all those people from all over the world she still manages to run into someone she knows. My wife and her talk while me and the boys hang around waiting just like we've had to do at our local grocery store back home. My kids and I still laugh at that story.
I’ve read about the “international airport paradox” which says you’ll likely see someone you know at an international airport - because if you’re in the group to use them, you’re already in a pretty small group.
I've actually run into people I knew in Manhattan. But they were from the Northeast so it wasn't that unusual.
San Francisco doesn’t feel dense to me at all.
San Francisco is the 5th densest county in the USA, the top four are also the four densest burroughs of New York City.
There is a good argument that San Francisco could and should be denser than it is, but its ludicrous to call it not dense at all.
I live in a US city with a higher population density than SF that has barely any structures taller than 3-4 storeys. Most of SF is low density for a city of global importance. The Richmond, Sunset have essentially not changed since the early post-war era.
You can argue the global importance of Silicon Valley or even California generally. I'm not sure I get the "global importance" of the city of San Francisco specifically, which besides an attractive location and relatively easy access to Silicon Valley isn't especially unique among medium to large US cities.