Thanks for the photos. I can really get a feel for the area now. I took one look and said, "Orange, yellow and white would brighten it up!"
Dahlia, Peony, Lilium, Hemerocallis, Roses, Clematis are all excellent suggestions with annuals for another pop of color.
Here are two photos taken by Spencer Barrett of the University of Toronto (used on ATP/NGA with his permission).
I like the look of Creeping Phlox even though it is much shorter than you might want.
Edited to fix link to photos.
