My favorite route is Highway 97 through central Oregon, Bend, (detour to) Crater Lake and then rejoin I-5 at Weed. From there just go straight down I-5 to Disney.

I prefer to drive north on 101 because the sun won't be in your eyes and you can see the sights much better. It's a long drive though, I usually book at least three days to do it, LA to SF in one day, SF to Eureka day two, then Eureka to Florence on day three. Day four is headed home to Portland.

the SF to Eureka drive is a short trip, but I always take the old highway through the Redwoods which adds another two to four hours between the increased distance and all the pit stops you'll want to take.