Do you have vast lawn areas or areas under newly planted trees and shrubs that you want to plant? When you are just starting a garden, or you don't have a lot of trees, or your trees and shrubs are small, a sun loving ground cover may be your best option. Ground covers are not only lovely to look at, but they also fill a need by holding soil in place and keeping weeds out. You can use them where you can't or don't want to mow. This would include hills or vast open areas that would be too cumbersome to mow.  You'll save fuel too.