I've been growing grapes in the Puget Sound region for a number of years. Pure Vitis Vinifera type grapes are prone to many root and foliage diseases. The "Champaigne" grape is very sensitive to powdery mildew. I have about 80 varieties of table and wine grapes up near Tacoma and could suggest several, depending on you growing season length and heat accumulation. Most grapes need at least 1,700 degree days accumulated above 50 degrees F., during the season to ripen their fruit.
Most of the well-known Vinifera types need over 2,000 gdd/50 to ripen.
Contact me for some more details.
You can grow some awsome grapes in the Northwest, but you won't find them at the 'big box' stores. I have one called Richard Walden that is very resistant to botrytis and mildew that does pretty well locally, and is seedless. It has Flame Seedless as a pollen parent and is also seedless.

I am technically in zone 8, in the middle of the Oregon wine country (Chehalem Mt appelation), but up at 1600 ft. so probably more like 7a in some spots. The wall I described gets full West sun and southern sun from about noon on. Other than that, our temperatures are about 6-9 degrees cooler than the Willamette valley floor and our general weather systems about like yours.