My third suggestion, today, of Gelsemium sempervirens. The crossvine has not been as dependably evergreen for me, and I am in zone 7a. It will be interesting to read of other people's experience with these two vines in your zone.

I'm in 6b and my Crossvine usually keeps it's leaves over the winter but they look kind of sick. They kind of shrivel a little too so it isn't realy evergreen. Then in Spring it regrows new nice looking leaves so if you need good cover all year it probably isn't the vine to choose. On the other hand when it blooms in the Spring it is spectacular and attracts hummingbirds!

ghoghunter: when you saw leaves look sick and shrivel are they still green or do they turn more of a brown color? I'm looking for a true evergreen flowering vine to grow in zone 7 (although I think where I specifically live is pushing zone 6) and am curious more of a description of what happens to yours in the winter.

Here's a picture I just took of my Crossvine. You can see that the leaves stay green but have some spots and stuff on them. These are the leaves that have been on all winter.

Here is a link that might be useful: Crossvine in March