How do you landscape a steeply slanted and tilted backyard?

I'd need plants for along the "stream bed" that don't require too much attention and can withstand clay soil, and full sun. All I can think of is ajuga and violets, but I would like a few plants that are 8"- 12" tall, too. Oh, there's one more problem.... DEER. Deer wander through our yard in the pre-dawn and post-sunset hours, so all plants and shrubs have to be pretty much deer proof. (One doe even gave birth at the back corner of our property where we have a pile of lawn and hedge debris piled up.)

The back of the property is high and to the south. The yard slopes down to the north toward our house, so any flowers planted on the hill face south and we only get to see the backs of the flowers.

I want to reduce the amount of lawn that needs to be maintained and create a natural setting for birds and animals . At some point in the future we will downsize and the back yard should be attractive and low maintenance when we put our place up for sale. We've thought of extending the deck, but at two lower levels, to make it more multi- functional and at the same time reducing the lawn area. If we put in a faux dry stream bed, with low care plants among the rock edges, that would reduce the lawn area and create interesting texture. Trees can grow in our shallow soil if they are small enough (2'-3'tall) when planted, and I thought that dogwood, redbud, and hemlock might work and be inexpensive to acquire. A couple of azaleas and some evergreen shrubs might be good, but they would have to be somewhat deer proof. It's a big project, but done in stages, over the next five years, I think we can get it done.

Erosion isn't much of a problem, because we have grass, and some bushes on a steep section, but there is no pazazz to the yard.

What kind are you thinking of? I've thought of decorative, tall grasses, but they can become invasive when the wind blows their seeds to a neighbor's yard.

The clay soil is not very deep and then it is bedrock. Everything we plant must have a shallow root system, or be able to find it own water source by sending its roots between the layers of the rocks. Grasses grow well in this condition, but I couldn't contain them very well with a garbage can, I'd have to jack-hammer a hole to sink a garbage can in the ground. Do you know of any grasses that wouldn't be invasive? I think that IS the nature of grasses. I don't want my yard to become our neighbor's headache.