Not sure I understand your post. Are you now thinking of driving straight to the coast instead of trying to include Yellowstone AND the coast in this 2-3 week trip?
If so, I would take as much time as possible. I consider the best part of the West Coast to be from the Redwoods in Northern CA and along the whole Oregon Coast. Oregon has great State Parks. Most people recommend driving the coast southbound as the scenic pullouts will be on your right. Certainly easier, but I've done a few trips northbound anyway. Summertime is busy on the coast, so reservations are recommended. There are also Forest Service, County, and private campgrounds. Relax and take your time with the drive along the coast. You'll be in the company of many many other RVers.
If you search the forum (not just in Family Camping) for "Oregon Coast" or "Redwoods", you'll find lots of info.