Rather than posting this question here, you might want to try posting it on the Virginia area forum. I'm sure there are lots of people there who could give you some good advice.

Bulbs would make pretty accents but they won't hold the slope together. How about daylilies for that slope? the naturalizing type of daylilies would do great on a slope, need very little maintenance and would multiply like crazy over the years. When they are blooming they are spectacular and even when they aren't, the leaves are pretty.

Here is a link that might be useful: Virginia Forum