California has an abundance of flora (more than 5862 species and subspecies of native plants according to  Arvind Kumar) largely in part to the varying topographical land features that range from mountains, valleys, deserts, plains and waterways. By planting natives in your garden you will attract native fauna such as butterflies, birds and other critters as you are recreating their native habitats. Keep in mind though, that if you want life to flourish in your garden you will not be using any pesticides, herbicides, fertilizers, or weed-and-feed, or chemicals of any kind as they may harm the wildlife.
Depending on the plants you choose, you may or may not be saving on your water bill. A common misconception is that when someone hears that a plant is a California native, they will require little to no water and they will flourish in your garden once they are established, but that is not always the case.  As mentioned earlier, native plants come from all across the state and are adapted to varying habitat conditions. For example Douglas Iris’ natural environment is moist and shaded grassland slopes in the coastal ranges of California thus they require regular watering. Whereas Ocotillo, a unique and structural shrub, is a native to the low desert regions of California and the southwest and requires little to no water once established thus it might to be suited to the cooler temperatures of Northern California. So when you are selecting native plants for your garden take some time to learn about their habitat and growing conditions, and take into consideration how you group them.
That being said, here is a small list of natives that fair well here in the Bay Area!

Coffeeberry (Rhamnus californica)
California Grape (Vitis californica)
Yarrow (Achillea millefolium)
Hummingbird Sage (Salvia spathacea)
California Fuchsia (Epilobium canum canum)