moonflower is great because it grows quickly, has large, saucer-shaped blooms, and it closes up during the day and blooms out atnight. It's called moonflower because its pale, lavender-white blossoms capture the moonlight and the blooms seem to glow at night. It's really striking.
on another end of the spectrum, you could try trumpet plant; it has brilliant orange, trumpet-shaped flowers that attract hummingbirds. It grows very quickly, but you can control its growth with pruning. has lots of bright green foliage as well.
a rambling red rose is nice too. there are varieties that grow very quickly and are fragrant as well (ask your nursery) .
whiteflowerfarms.com is a great resource. It's located in CT but can help with all kinds of questions for any zone.
I like morning glories, but care must be taken or they will rule the world! Prune!