Another option to traveling to the nearest open space for a hike is local City Parks. Some are pretty good sized. Many also have some kind plantings and maybe even a water element so they can also be great places for photography. I'm lucky to live near to several that connect to a local trail system.
For more info on these hikes and the park in general go to my hiking website at: www.HikingTheBayArea.weebly.com.