Unfortunately, there's not a lot between Phoenix and Anaheim that I'd call "fun." We live in Phoenix and make the drive at least a couple times a year to Orange County.
Heading west from Phoenix, once you leave the sprawl, there's not much except rest stops and truck stops until you hit Quartzsite, about half an hour east of the CA/AZ border. Fast food, a few gift shops that cater to snowbirds and rockhounds. We often eat a meal here.
Blythe is just over the border. Gas will be very pricey here (gas up in Quartzsite if you need to). Lots of fast food, not much else.
Then there's a really looooong stretch of nothing except rest stops and a very tiny dot on the map called Desert Center, notable only because there is a diner there with a relatively clean bathroom (I speak from experience).
When you hit Indio, there's a little more to see, but still not much I'd call kid-amusing. Palm Springs is probably your best bet if you wanted to make a half-day stop. There's a desert zoo, a water park, and the tramway up into the mountains. Just west of Palm Springs in Cabazon, there are giant dinosaurs visible from the freeway that you can walk around. Also an outlet mall in this area.
Sorry; I know that's not much for fun. We have four kids and usually just push through. It takes us about 6.5-7 hours with bathroom stops, a food stop and a gas stop.
If anyone else has found some "hidden gems" between Phoenix and OC, I'd like to hear about them too!!!
PHXscuba
p.s. DO NOT take the 60 through Moreno Valley in CA (perma-construction

). Stay on I-10.