re: Olympic National Park

Well I see your post above about going to Spokane and also having children. I'd agree there's so much else in the state the extra 6+ hours of driving roundtrip wouldn't be worth it for a day in comparison to the Cascades since that's on the way. You could do Snoqualmie Falls nice views, Franklin Falls (quick hike), stop in Leavenworth if you take highway 2, etc.

Now if you do end up going, I'd take a ferry (30 min plus a wait), the lavender farms (30 min), Lake Crescent (3-4 hrs or longer), and I've heard the hot springs would be a good day trip. There was a toddler with a diaper walking the Spruce Railroad trail so that hike is easy enough for kids and it's paved. No need to go all the way to the coast (La Push) unless you really want to, you can get nice views from the Dungeness park in Sequim as well on the way back.