Some good advice so far. Let's see if I can add a few things.
I agree about the Big Sur coastline south of Monterey; it is spectacular. From San Francisco, you can make it down quite a ways in one day, and still make it back to sleep in Carmel or Monterey, before heading east to the Sierra mountain range. All of the mountain passes have good views, but are quite different. I recommend you do Google image searches to see which interests you the most. 2-lane: Tioga, Sonora, Ebbets, Monitor. 4-lane: Highways 50 and 80. Ebbets pass is the narrowest, and also has some giant redwood trees (state park).
Bodie is a very well preserved ghost town from the gold rush era, and is the best one if that interests you. If not, Highway 49 along the west side of the Sierra is a very nice drive. (I live along that route, so PM me if you like) Lake Tahoe is not too far away, and also worth seeing.
Including Shasta or Lassen (dormant volcanos) would be cool, but will add lots of miles to your loop. If you plan to take the RV to Yellowstone, you could see them then.
Driving will be fairly relaxed compared with the bicycle lane in Amsterdam. Riding motorcycles over the mountain passes will be very different from the flats surrounding Amsterdam, though, so just take your time and be safe. Americans don't follow the rule requiring slow traffic to keep in the right lane, so many people pass on the right (breaking the law). I would recommend locking the bikes and helmets wherever you go. Most areas are pretty safe, but the high theft areas best known to those who live near them. The Central Valley of California is probably the worst.
Enjoy your trip!