I'm trying to choose a clematis for my porch garden. I'm reading books about clematis but having trouble finding clear info on which one to plant. I'm looking for a climber that will grow over the porch rails, with evergreen foliage. This might be sacrilegious in a clematis forum, but I'm almost planting it primarily for the foliage (although I've lusted after clematis for years), because that is exactly what my porch needs.

I live in Vancouver BC, zone 6. My porch is south and southwest facing. If there's any sun in the area, we get tons of it. Winters are long and wet, summers are short and dry. In general I wouldn't call this area windy, but there are some windy days now and then, and the porch is definitely exposed.

Any suggestions? Anything else I should know? Thank you in advance!