Both State and City parks can be used for weddings. There is a fee of course but your money supports the parks so it is money well spent.You may want to explore the option of Lincoln Park in SF amazing views of the Ocean, bay and GG bridge.
I love this place. You re high on a hill. From one side you see the Golden Gate Bridge, from the other the Pacific Ocean (through the trees):http://www.herecomestheguide.com/locatio��