All good suggestions. Coleus came to my mind, always colorful. Mix and match, including green olives.
http://www.rosydawngardens.com...
German Yellow
http://www.rosydawngardens.com...
Rustic orange
http://www.rosydawngardens.com...
There are a bunch of coleus that would look good. Endless possibilities.
And impatiens in salmon and orangey tones. And some white to brighten it up.
Karen