The drive from north to south is THE way to go, so good for you. My feelings are...it is all about whether you want to make miles or see stuff. If it's miles, the 101 doesn't make it. But..if you want to just take it all in? Take I-5 to Olympia and hang a right off to Aberdeen. Once there, bear right and up the coast a bit to the best Wa State Park...AT the beach..not ON it. Pacific Beach. My issue is cost. It's going to be $100.00 per night.
Head south on 101 and just cruise. There are state parks and national parks all along the 101. Stop every chance you get..all the small towns. We keep our phone on and my co-pilot is looking at every spot, on-line..learning what's what and if we need to go see something. This way..took us three weeks last year to get to San Diego.
Gary Haupt