There are three potential layers to planting in the garden, the tree canopy, a shrub layer, and the ground cover. There are beneficial purposes to wildlife in planting all layers, but this also serves aesthetic and practical goals in minimizing labor to weed. My primary concern has been developing a garden that pleases me, but encouraging wildlife has become a close second.
Hostas, hellebores and barrenwort (Epimedium) edge this stone path.
The most practical aspect of planting to cover the ground is to minimize weeding. Only the lower third of the rear garden lacks a complete covering of planted areas, and here I spend most of my labor plucking weeds that won’t give up until there are plants to cover every inch. I’m working on it.
Both are looking a bit haggard in our late summer drought, but a yellow leafed carex and the native Allegheny pachysandra spread along the driveway. I’ve planted a number of carex varieties in both sun and shade. The native pachysandra is considerably slower in growth than the more common pachysandra.
There is a bit of trial and error in figuring which plants are best in the varying soil types (moist and dry) and sunlight exposures. I also evaluate ground covering plants for their growth rate. A plant that slowly creeps must be purchased in large quantities or planted only to cover a small nook. More vigorous plants must be easily controlled, and they must not overwhelm neighbors when I’m slow to chop them back.
I’ve planted large and small leafed ajugas to spread in part sun and shade areas. While most of the ajugas are purple leafed, I’ve planted a few with green and variegated foliage that are slower to grow. Ajugas will probably spread over a patio if given the opportunity, but it is very easy to keep within bounds.
While sedums are used extensively in this garden to carpet areas in sun and part sun, there are many other low growing plants used for similar purposes. Below are several superb ground covers that assist in minimizing labor, but also are beautiful.
Cypress spurge (Euphorbia cyparissias) has seeded itself a dozen feet away from the original plant, but I have little concern that it will be overly aggressive. The initial clump was overrun by a seedling of Geranium ‘Espresso’. In two years the original plant disappeared completely under the canopy of the slightly taller and obviously more aggressive geranium. Leaves of other geranium seedlings can be seen below the spurge’s foliage. These will be weeded out so this textural foliage is not lost.Golden Pacific juniper is found under several trade names. It is a mounding juniper with excellent color even in midsummer.Green and Gold (Chrysogonum virginianum) spreads to cover open ground, but it is never a threat to overrun neighbors. Some gardeners curse Creeping Jenny (Lysimachia nummularia “Aurea’) as too aggressive, but it is easily controlled. Here, it is growing up into the dry gravel of the rock garden where it must be snipped out so that smaller plants are not overwhelmed.Strawberry begonia (Saxifraga stolonifera) is useful in damp shade where it continues to spread but is easily controlled. The low growing, evergreen Plum yew (Cephalotaxus haringtonia ‘Prostrata’) grows in shade and is deer resistant. It does not spread this protection to the hostas growing by its side that must be sprayed with a repellent.
Ramblin' through Dave's Garden 
I the ajuga picture, what is the variegated gingko? I presume that the plants in that picture are in part shade?
This area gets a few hours of afternoon sun in summer that slips below the tree canopy. I think the ginkgo is Jade Butterfly, but I lost the tag.
Excellent timing! Just trying to figure out what to plant in my new part sun/shade garden with some ground cover and some perennials.
Good timing – planning a new large bed with shade and some sun with groundcover and perennials!
I am also planting a new area after tearing out long established plants. I have no shortage of plants I want to cram into this small space.