If you have some large planters and want a larger plant, Hibiscus moscheutos will do well for you. Very hardy. Spectacular in bloom but leafless during the winter. Rock garden plants should do well if you can give them some shade and mitigate any harsh conditions during the summer.
Sempervivums are interesting smaller plants that change their coloration as the seasons and conditions change. Usually very hardy. I give mine no special treatment over the winter.
Vinca minor 'Variegata' has good foliage year around and beautiful blue/purple blooms in warm weather. I've added a photo of some of mine in a small pot.
Violas will work. Many of the lilies will work but they will be dormant in the cold weather. Beautiful in bloom though. Crepe myrtles are good although they, too, will be leafless most of the winter.
What size containers do you have?
