1. When you ask for "coffee" in a diner or something, you get some terrible drip-filtered gack. No wonder Starbucks has stomped all over the USA. By way of comparison, even the smallest eateries in Brussels have coffee machines that make a passable espresso and decent coffee.
2. Buying public transport tickets is a great way to get rid of even the smallest loose change. Over here, this stuff accumulates to levels at which you could store them as ballast in a ship's hold and use them for shrapnel in it's cannons. On the buses and trams in SF you can pour fist-fulls of the stuff into the machine and it'll sort and tally it all correctly.
3. The SF tagline should be "the Yoga and Tai-Chi capital of America". Get out early enough and you'll see any given green space has a cadre of people doing their exercises.
4. The place is surprisingly bike friendly, provided you stick to the costal areas. Enormous great SUVs give you half the lane to play with, as if they'd rather suffer a head-on collision with another motorist than a mental health lawsuit from a mildly claustrophobic cyclist.
5. Everyone is friendly. Cool, interesting conversations were had on diverse subjects such as the psychology of addiction, the concept of currencies, long term geographic effects of global warming on property prices and purchase strategies, the LT, WTFDNU, etc. This stuff is slowly permeating through into the general conciousness.
6. Geeks are everywhere. Trying to sleep on the plane when your brain is randomly plucking tech words from surrounding conversations is like trying to sleep during a Windows install. You know there's nothing better to do [except fill out your product registration card!!11 :-P], but something might come up that makes life interesting.
7. T-shirts: saw a T-shirt with "Dept of Homeland Security - since 17nn", and a picture of four Native American Indians with muskets. Hahaha.
8. The Apple store in SF: It's JUST A STORE. Why people queue up outside of it every morning is totally beyond me, nice machines though they be.
 Why yes, I happen to be reading The System of the World, which is a fantastic Stephenson, and which also contains the best Monty Python Joke Ever.