Landscaping help for large, steep hillside?

If the terrain is steep, I would think you'd want to cover as much as possible with plants and skip the mulch...a heavy rainstorm could wash away the mulch and any dirt that the plant roots don't reach. I would say daylilies would be a great choice...you can get them cheap and they survive almost anywhere...if you plant a bunch of different varieties, you can have color for a very long time. The vinca can be nice, too...give you some early color before the other stuff blooms.