Vinca grows in a viney fashion with glossy green leaves with a blue flower appearing in spring. When you are purchasing flowering plants for a shady place try buying the varieties with lighter colored flowers because they will show up better in the shade. In especially dark, shady places it is particularly hard to get plants to bloom. This might be a good place for perennials with interesting foliage. It has attractive wide leaves and can be found with stripes, green and bluish foliage.
Ferns are also a great way to deal with the shade.
It almost looks out of place to see a fern growing on the Wyoming high plains, but will grow fine here if you grow the right types. They love the north side of buildings. The ostrich fern is a good choice for Cheyenne. Both types can grow up to two feet high and can even spread. I received my ferns from a neighbor who was being inundated with them spreading under her junipers.