I enjoy Rozanne and Alba Geraniums (Cranesbill). You might also like Zephyranthes candida, which is a bulb. It has evergreen strappy foliage and blooms repeatedly through summer. It looks great year round on the front of my border.

the little-leaf zinnia (zinnia angustifolia) keeps a tidy habit and attracts butterflies. needs a good bit of sun.
the "profusion series" zinnias also are mounding with larger flowers.

Jillie, I can think of several annuals that fit your description, like the great zinnias that Jeff mentioned. Are you sure that you want perennials for this job?

not really. i was only thinking perenials bc then you dont have to worry about them for awhile. i am not opposed to annuals.