I think a climbing Hydrangea would be very nice and not heavy like a Wysteria is. The Clematis I believe are deciduous here but I am nof familiar with all the varieties so maybe there is an evergreen? More importantly though for the Clematis is that it may not get enough light there. You probably have room to consider breaking up the space with some flowering shrubs as well as climbers. Rhodies and Azaelas are a Northwest standard and are stunning when they bloom. They are also a huge family to choose from so you can really achieve a lot of variety with them. Sizes, color, leaves and light preferences are some of the variations within the Azalea/Rhodi family.
You might also consider Camelia or bush hydrangea.

Honestly though the PNW is a great place for plants and your options are guite extensive. You can safely give some thought to how you might want the space to look first and then find the plant to fit. You could break it up so it looks like a garden or stick with the hedge shape. You could use Rhodie/Azalea with different bloom times, a fence of climbers or a variation of both and so on.
I am from the desert South West and I am thrilled with the selection up here.
I think one of the most important things to consider in the PNW is the micro climates. It is amazing how impactful these can be on your success or failure. Really take a look at what is going on in the specific spot your are considering and in your case you may have several micros along the length of that hedge. That just gives you even more options.
Oops, probably just made it more complicated for you. LOL

Hydrangea seemani is a great choice. evergreen, takes full shade, flowers after a few years. also, it will take up WAY less room than a photinia hedge.

i have a soft spot for different mahonia varieties. you can plant a couple different varieties and ensure a constant flower show from december till april. only getting morning sun wont be a problem. most are pretty easy to keep in check with pruning.

i would also look to an osmanthus of some variety as well. also does well with 1/2 day sun. flower and fragrance. evergreen.

realistically you have about a million options, lots of people will have different favorites...

The evergreen hydrangeas are tender. I have seen some damage after this past winter, total or near-total death in 1990. If there is room and you are willing and able to do some effective pruning and training anemone clematis produces a curtain of growth studded with abundant small flowers May-June. Some forms sold here are also fragrant in bloom.