You've got way too much planned. Your kids will hate you, your friends won't be your friends anymore, and your spouse will want to divorce you. You'll get to see the inside of your vehicle a lot and have precious little time any place you stop. If you're stopping to see friends, that's not just an hour visit. I think the most important people to think of are your kids. I've never met a teen that wants to spend hours a day for days on end driving in a car.
Below is what I'd recommend. If you follow the links, you'll discover a wealth of information for a trip that will be full even with three weeks.
The first cut I would make would be to eliminate going inland to Las Vegas, the Grand Canyon, Monument Valley, etc. That area is a three week trip by itself. Save that for another trip the following year.
Next, I'd take a good hard look at the need to head all the way south to Disney. In many ways, if you want to visit SoCal, it might make more sense to fly in and see not just Disney, but also Knotts Berry Farm, the San Diego Zoo, Sea World, Safari Park, etc. This type of trip is better done in a car as driving a trailer around SoCal traffic isn't fun.
I imagine you've done quite a bit of camping in those gorgeous mountains near you. So thinking about a trip with different experiences that your kids will love, I've come up with the following ideas:
Camp at
Deception Pass SP north of Seattle. Take a day ferry trip to the San Juan Islands (kids seem to love ferries). If the season is right, catch a charter out to whale watch. There are charters out of several of the island harbors.
Also in WA is Mt St Helens. There is access from several directions. It's amazing how much the vegetation is starting to reclaim the devastated zone around the mountain.
From there, head south to the Columbia River Gorge. Lots of short to intermediate hikes to some great water falls. Check out
this brochure to get an idea of how much there is to do there. Easy access to Portland from this area.
From there, I'd head to the coast. While the WA coast is nice, the OR coast has easier access for a much greater distance. The OR SP's are among the best. Reserve ahead as the popular ones get full in the summer. The area around Canon Beach is quite popular and touristy, with lots of entertaining things to do (it's closest to Portland, so gets lots of weekenders). As you go south, there are less crowds but no less stunning scenery. Among our favorite CG's from our last trip in the south: Harris Beach, Beachside, Sunset Bay all with walking distance to the beach. Tillicum Beach NFS CG only has a few sites with electric, but also has great beach access.
So much to keep teens entertained along the coast. Sea Lion Caves, Tillimook Cheese Factory (think really great ice cream), sandy beaches and tide pools. Last time we went, we spend two weeks just on the southern half of the OR coast. Download
this brochure on light houses to see if there are any you might like to see. Download
this brochure on tide pool inhabitants and take your kids out to look at starfish, urchins and crabs (things not often seen in Alberta!) Print out this
tide table and go at low tide to see the most critters.
The Redwoods of northern CA are impressive. We stay at Harris Beach SP in southern OR and drive down to the Redwoods from there. CA SP's have just gotten so expensive.
There are interesting beaches along the CA coast north of CA some with camping within walking distance. But at some point, it's time to turn and head for home. I'd come back on the inland route. First head to Mt Lassen Volcanic NP. Besides the volcano, which erupted 100 years ago, there are interesting thermal features.
Bumpass Hell Trail Guide Devils Kitchen Trail Guide Nothing to compare to Yellowstone, but something different the kids would enjoy.
From there head north to Lava Beds NM. Explore the
lava tubes. Your kids will love to explore as most of these tubes are unguided. Bring flashlights or led headlamps. We also had bicycle helmets to protect our heads. They also lend flashlights at the visitors center. The
campground there says up to 30', but we've seen bigger units in several of the sites. When we were there last, our PUP and 4Runner combined were nearly 40' long.
Cross into OR and go to Crater Lake. Take the boat ride out to Wizard Island. Spectacular setting.
Further north in the Bend area, there are more lava tubes to explore. We like to camp at
Newberry Crater NM. There are NFS CG's around East and Paulina Lakes that are great. These lakes are in the bottom of an old volcano, so it's like camping along the shoreline of Crater Lake. While there, check out the short Obsidian Trail and don't miss the Lava Lands Visitors Center (see the Newberry guide linked above). We often spend a week in the Bend area.
At this point you'll be out of time and have to make a bee line for home.