I live in Oakland.
Union square is ok. I haven't been there more than a handful of times since moving here over 5 years ago. It's kind of like the high-end shopping areas you'd find in any big city. But it is right next door to Chinatown. The only real touristy stop I'd recommend wholeheartedly is Alcatraz. Well, and the Golden Gate bridge, of course. We love our damn bridge. The classic way to enjoy the bridge is to ent a bicycle for the day, bike to Sausalito, then ferry back. I grumble all the time about the tourists crowding it when I just need to get to Marin, but they're all having a fabulous time.
Go for a run in Golden Gate park. Seriously beautiful and peaceful and home to a couple of excellent museums. Elsewhere, the SF MOMA is also fantastic. The heartbeat of the city, IMO is in the Mission/Castro area, where you'll find great restaurants, great coffee, lots of young techies, the gays, and Dolores Park (if you luck into a warm weekend, definitely go to Dolores). I've been in the Mission right up to the 23rd and the sheer volume of people living in such a small space means that it won't die off too badly.
There's a starting point...I'll maybe give it more thought later.