San Francisco is a giant playground, its just a matter of finding the right places to play... Here are a few of my favorites:
1. Sutro Baths- below is a picture of what it used to look like, and following is a picture of what it looks like now Its a really fun place when your looking to get away from the city feeling. There are caves and other things to explore, and there is a breathtaking view of the Golden Gate Bridge.
2. The Giant Camera you have to pay $2 or something to go inside, and it's worth it!
3. The Castro Slides, they are sort of a secret of san francisco, but they are amazing! Enjoy!