Until last year I always only put annuals in pots. Then I heard someone say how great some perennials were. Perennials are an improvement since you don't have to redo the whole shebang, maybe just tuck in some annuals for a somewhat different mix each year. I try for something low and cascading, something tall and spikey-leafed, something medium height and bushy. Often something burgundy-leafed or silvery-leafed looks great with the greenery to relieve monotony. Just make sure they have the same water and light requirements.
Will it be full sun?