I've driven 101 from as far south as Los Angeles to as far north as I could go. I don't think it goes all the way to Canada. It goes north along the coast to La Push, WA and then cuts across the Olympic Peninsula to Port Angeles, WA. Then it runs west to Port Townsend and turns south to Shelton. From there it goes southwest toward Olympia, where as far as I know, it ends. The US/Canada border runs down the middle of the Strait of Juan de Fuca, and Port Angeles is on the south shore of the Strait, but I think that is as close to the Canadian border as 101 gets. You can take the ferry from Port Angeles to Victoria, B.C. and cross the border that way.
In any event, it is well worth driving. My suggestion would be to drive it north to south for the best views of the Strait of Juan de Fuca and the Pacific Ocean. I hate driving any route through the San Francisco bay area, but I think 101 through SF is a bit dicey with an RV. Hope you enjoy your trip. You've chosen a beautiful area to explore.