Do you get frost or freeze? If so the lantana will turn black in Jan. Do you really want to be on a slope every year and cutting it back as it won't leaf out on the longer branches. It can get leggy after a couple years and needing cutting back anyway. It will quickly cover for ground cover but for erosion if heavy rain it won't stop a slide as the longer branches don't root.

Good article on erosion control for California slopes here:
Planting a slope

Depending on your location, the steepness of the slope, etc, low maintenance is a good idea. My front slope is planted with Aloes, Agaves, and other xeric plants that need little water and no trimming. The different colored foliage provides color year round.

Hi, thanks for the answers. I rarely get frost. Maybe once every few years we will get a little frost. I have lantana in my back yard and only had frost damage once a few years back.
But it does happen, so that is a good point. It will be a huge pain to have to cut back an entire hillside!
Hoovb... thanks for that link. I think I am going to go with some native plants and make it a wildlife habitat!

Sunny Slopes & Plants that Hold Them! This is a good article on a few suggestions for planting slopes with native species.