:) I'd look no futher than the local highway...

since most of the medians in the bay area are covered in something called 'ice plant'... a succulent that grows like a weed if you water it ever other week, and makes nice fuscia or red flowers in february.

one of the other most used groundcovers is prostrate rosemary- which flowers in august or september, and if the slope's not close to the road, you can harvest it for shish kebob stakes and seasoning :)

I would check around the nurseries for local groundcovers in the succulent families- drought toerance IS an issue in most of NoCal, and there are quite a few foliage colors (silver, blue, purple, red) to incorporate (my 'lawn' was about 6x10, so I didn't have much room to fill in) but ideally, you want a shrub or three with roots that go down deep, then a shorter shrubby thing- lavender is a natural choice that does really well on a slope, which will prevert crown rot when it rains for 28 straight days ;)

and a truely prostrate or short creeper. the varied root depths will hold the slope together better than anything else

Consider "Coyote Bush" (Baccharis pilularis), a California native. Attractive green foliage combined with a tolerance of alternating wet and dry conditions. I've seen pictures of it on slopes that are very attractive. And the plant is available at Las Pilitas nursery (www.laspilitas.com)

Kristi

Here is a link that might be useful: Coyote Bush

I do NOT recommend ice plant as a GC for erosion control. Here in Southern California, they blame ice plant for many of the landslides, because it is so heavy that it takes the dirt down the hill with it. Look for non-succulent drought-tolerant plants with dense root systems: rosemary, vinca, ivy, gazania are a few good choices, although they can be invasive. Check Sunset Western Garden book; it has a long list of plants for erosion control. Also, it's a good idea to mix plants, ground cover, and large shrubs such as oleander to best hold a hillside together.