My first thought was lilies. And large dahlias or hydrangeas. I guess anything with a big or bold bloom, or unusual color, IMHO.

Dee

I like the idea of perennials- I was just thinking annuals.

Lilies... oh the possibilities!
thanks!

Sweet Peas. Of course. :)

Any lily or dahlia

One year I grew some Iceland poppies, a flower that is seldom seen in Arkansas. For about 2 weeks I kept one or two blooms in a vase in a business reception area. They looked so perfect that about 4 out of five felt compelled to touch them when they thought you weren't looking, to see if they were artificial. When they discovered no stiffness, then would come the question "Are these real?"

An artichoke in flower is spectacular and doesn't need anything else to set it off. It would be easiest in your zone to get ones that will easily flower their first year and that you can treat like annuals.

I would have a hard time growing artichoke. I like eating them too much.
I am growing a dahlia called Pennsgift which is supposed to make monster blooms provided you snip off the side shoots. One of those will make quite the statement. I may well need a concrete vase so it doesn't tip over from this sucker being so top-heavy.