Now that I see a picture, how wide is that area? Most plants that are going to get 5' tall are going to have a wider base. Is there room for a 3-4' wide plant there? Since you want it that tall, are you trying to cover the brick?
I read a bit on landscaping to prevent erosion, and it seems that native plants are the best way to go - the taproots tend to go deeper than cultivated plants. Not only that, but they will be naturally adapted to your soil conditions and rainfall, so less maintenance!
It also seems best to use plants with a deep taproot interspersed with plants that have many shallow roots. As the roots mesh together, the deeper roots with hold down the shallower roots.
Think of it like nailing a net over it.
I'm going to suggest clumps of ornamental grasses, with a low groundcover between them.