I'll share my thoughts as I go to help out anyone planning on going to California anytime in the future.
From the airport the BART is the way to go. $9 to the city and it's about 35 mins.
Had a great weekend in SF. AT&T ballpark is awesome. No bad seats in the place. We sat in the 3rd deck in right field and the seats were great, unreal views of the bay. Alcatraz is a great take too; definitely worth it.
Hit zeitgeist, a cool bar in the mission with a big outdoor area. Hipster kind of vibe, they only serve craft beer. If you like culture then the mission district is great, tons of food options. The burritos at La Taqueria live up to the hype but be prepared to wait in line, especially on the weekend. I also got a pupusa from the Salvadoran shop next door and it was the best Papusa I've had in the states. Tasted just like the ones I had in El Salvador. If you've never heard of a papusa it's like a thick grilled tortilla stuffed with cheese and something else. I like mine with cheese and pork.
Nob hill is breathtaking, it's so high and steep you almost have to see it to believe it. Chinatown is awesome and authentic, also really big.
We rented bikes and rode over the Golden Gate Bridge. We did the long route and hit Sausalito, mill park, and then tiburon. It's a pretty tough and hilly ride even if you're in pretty good shape. Sausalito and tiburon offer amazing views of the bay and city. Mill park is a small park but has some beautiful and huge redwood trees. We grabbed drinks and some food at sams in tiburon which has a huge deck on the water with views of SF. We took the ferry back to the city.
We Hit ghiradelli's for desert; good Sundays but pricy, crowded and touristy. Fishermans warf is ok but we didn't spend much time there, too many tourists. North beach is a nice neighborhood and the walk up and down from the coit tower is pretty cool.
All and all it's a pretty stunning city. The geography and views are unique and the best part. Everywhere we went felt extremely safe. The public transportation isn't the best so we mostly ubered or walked around. The cable cars are more for fun than function it seems. They only cut through a little bit of the city. The weather is odd. Usually cool and cloudy in the morning and the sun tends to come out in the afternoon. It has been kind of cold and constantly windy in SF and way nicer and sunnier outside of the city. If you've never been to SF it's a must see American city.