I live in Texas so I might not be much help. But I will throw these three out there, they are show stoppers. The first is the easiest to grow and reliable to come back-- lilium. Check out the lily forum great pictures!
The second would be peonies. They are beauties once established. The flowers that I get the most comments on are clematis-- large jackmanii type. They are more vertical. People think they are hard, but the secret is a strong rootball forming before you let them bloom. These would do great in your area and once established easy to take care of. May your endeavors be blessed!
