Ohhh I think anything cascading would be awesome in a container.., UNless you want something with height to use as a back drop! I agree that blue daze is pretty BUT the only thing is ~is that it is suppose to be heat drought tolerant And I seem to have to water mine more than a heat drought tolerant plant should need, and seeing how we pretty much have the same temps in summer it may be a problem, I don't mind watering mine tho because I like the results,
Also vinca( periwinkles) cascade.. Ohh and the Dew plant absolutely is heat drought tolerant.. and has pretty blooms too that continue to bloom spring
thru fall!, If you want something somewhat bushy you can grow Dahlia in the larger containers that will also bloom thru summer and fall.. or even Sun flowers
or black eyed susans,,,, There are soooo many to choice from, ,, I'm sure you'll get a lot of suggestions!!!