This slope was landscaped with boulders, with shrubs planted randomly amongst them. It is definitely more preferable to a barren hillside, but the addition of shrubbery with more color and texture will help enliven this palette.
For your front yard perennial garden. Nepeta Walkers Low, salvia, artemisia, and autumn joy sedum could give you this look. Designer Plant Combinations: 105 Stunning Gardens Using Six Plants or Fewer : Scott Calhoun