Trachleospernum jasminoides is a great evergreen for a warm site with some sun and there are a lot of them about in instant sizes fairly cheap shipped over from Tuscany but it will not stand cold saturated roots in winter. In the shade you can't beat the evergreen Pileostegia viburnoides for complete cover, but it is slow to get going and hard to find.

Don't overlook hedera colchica

I'd try and avoid clematis species unless you like interfering as all Clematis naturally tend towards bare stems at the bottom and leafy growth and flowers untop as they have evolved to grow through trees etc. so they don't really screen much.