Highway 101 - Is ZERO problem to drive. There are some slow, hilly and curvy areas in Oregon but the actual drive is not difficult. Traffic can be very slow in the summer months due to volume.
I will tell you that once you leave Oregon headed north, there is little to see of the water on 101. Beautiful scenery but lots of long areas of large evergreen trees....... I prefer to drive the Oregon coast and then cross east over to I-5 headed through Washington.
Alaska route - I suggest you look at where the tour companies such as Adventure Caravans and Fantasy go. They post itineraries online and they will show the areas you might like to see. Once in Alaska, routes are pretty limited that everyone travels. Be sure to get a current Milepost to assist planning. We did an Adventure Caravan and loved the entire trip.
Alaska hint: Plan your fuels stops. Can be MANY miles between fillup possibilities. Some remote fuel stations may not still be open.......
Let me know if you need help with where to stay in WA on the way north. Seattle has almost NO RV parks in the vicinity. Happy travels!! Sounds like a great trip.