When will this be?
I've done this drive (or something like it) so many times that I really can't recall. I MUCH prefer the coastal route, even though it takes 3-5 hours longer than I-5 wheels turning. I detest the Sacramento and Rogue Valleys (Medford et al) in the summer; it's too damn hot usually.
So if you're okay spending a night on the road, my preferred route is US 101 north to Reedsport, Oregon, then through the coast range on OR 38 to I-5 near Cottage Grove, then up the Willamette Valley to Portland. Depending on when you can get away from SF (from the city? Burbs?) you can spend the night anywhere between Gold Beach and Bandon, and still make Portland in a few hours the next day. Bandon is my preferred spot, but you'll need to book accommodation in advance, because many Oregon coastal lodgings require two night minimum stays (especially around weekends) in the summer. OR 38 is very scenic and is probably the quickest route from the coast to I-5. Map -
https://goo.gl/maps/vxfewRkGQzCuMw2z6
If you want to go the inland route, then I'd overnight in Grants Pass, unless you want to try to find someplace in Ashland. Ashland is cute but is inundated with culture types due to the Oregon Shakespeare Festival that fills every bed all summer long. Map -
https://goo.gl/maps/o73cPCgzTHtg1kVq5