Lots of great advice and ideas here!
We have done quite a few western trips. In summer 2018 we did the following.
-Flew into Seattle from the east coast. We arrived mid afternoon and after getting our rental car, we went straight to the Space Needle for a ride to the top.
-Beacuse of the 3 hour time change from the east coast, it is very easy for us to be up early. This is great because we can usually escape a lot of the traffic that people talk about. We were on the road by 5:00 am (8:00am for us, coming from the east coast, so not particularly early.) We drove to the Hurricane Ridge section of Olympic NP. We didn't use the ferry and it took us about 3 hours. We were driving up to Hurricane Ridge a little before 8:00am. Unfortunately for us, there were fires EVERYWHERE in summer 2018 and was quite smokey up there. Because of the smoke, we only spent about 3 hours and only did some short hikes. From there we went to Cresecent Lake. We stopped at quite a few pull offs and hiked to a waterfall. From there we went to First Beach. It was windy and chilly and we only stayed about an hour. We then hiked into Second Beach. Again, quite chilly. We then drove to where we stayed for 2 nights. Kalaloch Beach operated by the NP service. A dinner in the lodge and spent over an hour walking the beach.
-Again we were up early the next morning and drove to the Hoh Rain Forest. And rain it did!! It rained/poured the entire day until around 7:00 pm that night. We did two hikes in the rain, in the Hoh Rain Forest. We then went to Ruby Beach. Again it was pouring, but even with the rain, we walked the beach for about an hour. Had it not been for the rain, we had more plans, but ditched them as we were soaked to the skin, so we headed back to Kalaloch. After getting dry, we again headed out to walk the Kalaloch beach in the rain. Obviously we only scraped the surface of what Olympic has to offer, but it was enough for us.
-Up early to drive to Mount Rainier. We had no problems with traffic at all and I think we were driving into the park around 8:00 am. We had reservations at the National Park Lodge. I had wanted to stay at the Paradise Lodge, but it was undergoing extensive renovations. We spent around 4 hours at Paradise hiking, before continuing on. We pulled off at many pull offs to take in the views. Off hand, I can't remember the name of the place we stopped to hike at, but it was along a river and had a "swinging" bridge to cross. Very relaxing and no crowds. We had an early dinner at the Paradise Lodge and spent the evening exploring the historic area where the National Park Lodge is located. Again, we scraped the surface of what the park has to offer, but it was enough for us.
-We drove to Mount Saint Helens. We enjoyed this much more than I had ever imagined. My husband and I were 13 and 16 when it erupted, so old enough to remember. We stopped at a visitor center on the way up to Johnston Ridge. We watched the movie at Johnston Ridge and spent a couple of hours walking around. Unfortunately, the smoke from the fires was an issue here too. I don't remember the name of it, but we stopped at yet another visitor center, that was privately run. It was amazing and a highlight of the day!
-Between doing some traveling the night before and getting up early we arrived at Crater Lake NP by noon time. We had reservations to stay in the Crater Lake Lodge. It was our second visit here. We drove the loop around the entire lake and explored the area aorund the Lodge. (On our previous visit we had done two hikes, but didnt repeat those on this trip.) The next day we had reservations to take the boat to Wizard Island. Once at Wizard we hiked to the top and once back down we went swimming in the freezing cold lake!
-From there, we worked our way to California and the Big Sur.
We obviously didnt see everything and did a LOT of driving, but we loved that trip and I would do it again in a heartbeat!
-Another trip we did was Glacier. We spent 3 nights in the park, staying at 3 different lodgings in the park, The Glacier Park Lodge, Many Glacier Lodge, and the Lake McDonald Lodge. From there we drove to Crater Lake! Talk about a drive!!! But, we knew what to expect for long driving days because, we did our research early in our planning. A lot of the drive was gorgeous and we never had any traffic.
-From Crater Lake, we went to the Redwoods, staying in Crescent City.
-We spent a couple days in San Francisco.
-Spent 3 nights in Yosemite, staying at the Yosemite Park Lodge and a night in a cabin at Curry Village.
-Went to Kings Canyon and Sequoia NP, before driving down to
Disneyland.
Most people we know thought we did wayyyyy too much driving on both trips, but for us, we were fine with it. You know your family best and what you will enjoy as far as spending days to a week at one park. Some love to do it that way and some not so much. Lots of great advice from posters here! I hope that you have a fantastic trip!