I'd do US1 down the California coast and old rt 66 across the desert.
I have a friend that takes off alone on his Valkyre every year and has a half million miles on it. He goes west towards S Dakota and then where he feels like going. He has Honda shops he visits and motels he likes knowing the distance he wants to ride. No google maps, just what he feels like. Sometimes Bonneville, Washington, Oregon, etc.
