Last season I hit on the combination of a red gerbera daisy coupled with a burgundy coleus and "Blackie" sweet potato vine. It was simple but quite striking.
I'd probably go for a mix of annual tall spikes and trailers. Like bronze-leaf New Zealand flax (phormium tenax) or a red ornamental fountain grass (pennisetum sataceum rubrum), with alyssum, verbena, trailing nasturtiums or even tubrous begonias or fuchsias.
