Hi, If you have an area that's so shady that turf grass won't survive, then it's probably best to go with shade-loving ground covers. Of course, it also depends on what kind of trees you have. For example, if you have maples you may not be able to grow anything under them because they are very shallow-rooted and can kill anything you plant underneath them. If you have oaks or other shade trees, you will have better luck. As far as garden shape is concerned, it really depends on your personal taste, but in general, I think irregularly shaped beds are more natural looking than formal squares or circles. You can see a lot of different planting plans in our garden design section of this website. By the way, if you do happen to have mature maples, you may have to just mulch the area underneath the trees and add color by potting up shade-loving annuals in containers and setting them under the trees.