Just some ideas to throw around. I had to drive from OKC back to CA twice a year for 8 years. The best idea we found was to leave after work the day before vacation and drive for 4 hours. It just cut the next days time much better. I joined the Holiday Inn club (whatever it's called) as they have a lot of them on I40 and I figured out the milage and made reservations beforehand as it was cheaper that way. If you are on I40, it's 6 hours through NM and 6 hours through AZ. (about 3-1/2 from NM to Flagstaff). I don't know how far you are in MO but maybe the night before you could get to OKC. (240 miles from Joplin to OKC). When you hit NM, you gain an hour
We stayed in Flagstaff, drove up to the Grand Canyon that morning, checked out the rim, the hotel, saw the mules and then drove back down toward Willaims and spent the night in Barstow.
CA portion, I'd stay north by Universal Studios area. We stayed at the Beverly Garland Holiday Inn (don't know what it's called now). Since your kids are older, they may enjoy Universal. I am one that still enjoys seeing Hollywood and think it's fun for everyone to do at least once. Footprints at the theatre, the Kodak Theatre where they have the Oscars, the Disney soda shop, driving down Sunset Blvd, Pinks Hotdogs, Melrose, Rodeo Drive. (just some suggestions). We usually end up going down Sunset toward Santa Monica and head out that way after checking out to go to Anaheim to see the beach.
This is not going to be popular but with teenagers, I'd skip San Diego. Yes SD has an excellent zoo but so does OKC which you can make a weekend of. My older boys would have liked Santa Monica or Huntington Beach more and the rides in DCA then the zoo/Marine World in SD. Knotts Berry Farm now has the thrill type rides also in the Disney area. (I miss the old Knotts but my older kids love the new Knotts....go figure).
I'd spend a minimum 3 days in DL and then head over to Scottsdale. Anaheim Plaza is a good deal. We always stayed at BW Park Place but the price at Anaheim Plaza and the extra large rooms keep us going back there. There is no breakfast but they have refrigerators and microwaves in the rooms.
These are just my opinions and my older kids likes. The drive from OKC to LA, there is the OKC Memorial right off the freeway in downtown. There is the huge cross in Groome TX if you are into that. Texas there is the
eat a 32 oz steak LOL New Mexico we had to get out at a few rest stops to check out the red rocks that look like bee hives. Arizona, we took the Winslow off ramp to check out the Eagles, Winslow AZ song area. It's not much but was my time frame growing up so had to do it. "Standing on a corner in Winslow AZ, such a fine site to see".
Whatever you decide to do, enjoy! ***just a tip. When you cross over the Colorado River to CA, slow down. Always a CHP there as the truckers have to move over and do 55 in the right lane after doing 70-75 in all lanes in AZ. The one thing about this drive is you can see how vast the US is. You will go from red rock to desert to greenery. Also, the truck stops through NM, AZ have some of the cleanest bathrooms.
