We spent five days in San Francisco, but it took me approximately one day to fall in love with the city - this is definitely my favourite place in California.
The hostel we stayed in wasn't the best (they messed up our reservation so we ended up sleeping in separate dorms the first night, and it could have done with a lot of sprucing up), but that didn't really matter - San Fran served us well.
It definitely is a city of hills - I don't think I even got this good a workout in Yosemite! But it was worth it. Simply walking the streets and exploring the various neighbourhoods is a treat - every corner you turn there's something different, with endless cafes and restaurants (hardly a chain in sight - a nice change) and beautiful architecture.
The weekend we arrived was Memorial Day weekend, and we celebrated by attending Carnaval in the Mission (similar to Notting Hill Carnival but with a Latin American, rather than Caribbean, vibe) and watching a fireworks display over the Golden Gate Bridge, commemorating its 75th anniversary.
Apart from that we did the usual touristy fare - China Town, Union Square, North Beach (loved), Golden Gate Park and Haight Ashbury. I'm also slightly ashamed to say that we went to the very touristy Fisherman's Wharf. After meeting up with a Norwegian couple we met on the Inca Trail for a drink, we decided to go with them the next day. We had a good day - walked around the pier, looked over to Alcatraz (unfortunately our funds were too low to afford a trip over there!) and had a nice lunch, but it is just a huge tourist trap. It feels completely removed from the rest of San Francisco as it is so different from that quirky city brimming with personality - but maybe that's a good thing, because when I think of SF I won't be thinking of Fisherman's Wharf.
Mostly, as I said, we just enjoyed walking around and seeing the great variety that San Francisco has - ducking in and out of shops, and stopping for hot drinks to warm up from the cold (I held the common misconception that everywhere in California is hot!)
My only disappointment is that we were on a backpacker's budget - the number of amazing shops and restaurants made me yearn for a much bigger bank balance! Looks like I'll just have to return once I've made my million.