Something to cover a NE Wall

How about clematis varieties - clematis armandii is evergreen. I have a non-evergreen durandii on a NE wall mingled with a honeysuckle. You could also look into forsythia and winter jasmine.

I also have a NE facing wall, it has a climbing rose happily doing what climbing roses do. Sorry I don't know the variety, it was in when we moved in.

My first thought is to train a Garrya eliptica (kind of like you would a Wisteria), but you probably don't have a hundred years' to spare?(!) so, I could recommend Mme Alfred Carriere Rose for your particular situation, if you keep it trained well in a horizontal fashion. It is a beautiful cream climbing rose and has a beautiful scent, flowering for a long period of time. It is not, obviously, an evergreen, as you requested, but it's a quick grower, and flowers for most of the year (I had one, so I know, and people used to stop me in the lane and tell me how beautiful the scent was whilst they were walking their dogs past the cottage....)
There is also a semi-evergreen climbing Honeysuckle with pale lemon/cream flowers, and I can't for the life of me remember it's botanical name (sorry) that flowers late summer and smells completely delicious, but is an untidy grower, ramblings rather than able to be tamed and trained to a wall.

It depends what you're looking for really. If you do want evergreen, then perhaps go for a Firethorn/Pyracantha? which'll give you berries and flowers and evergreen foliage. If you decide you're not that fussed about the evergreen bit, fancy a bit of blossom and fruit, go for a Sour Morello Cherry.

World's your oyster really, and I wish you luck with whatevery you choose.