I think if you are living in a higher zone you have many more perennials to choose from, only 2 of Lin's first choice are perennial for me.
My 5
Hardy geranium
Columbine
Iris
Peony
Campanula (because of it's diversity of blooms)
Lupine would have made the list but it wont grow here for me .
I use to have beautiful ones in Michigan.
