Quoted from Max_Badazz:

Two day pass. You will want to hit up both parks with your kids. Both parks offer quite a few attractions for the younger crowd (my family loved CA Disney more than FL Disney). They are so different as well. California Adv. was way more laid back while Disneyland was more high energy as it has way more rides crammed in a small space. One has Cars Land, the other Star Wars land. Can't see one and not the other

Quoted from fosaisu:

Doing one day at Disneyland and one day at California Adventure makes sense if you want to get a majority of the rides in. But even then you're looking at long days at the parks if that's your goal. Could you include a "rest day" in-between to check out other stuff in LA? It was a few years back and my kids were a bit younger, but we did the beach and La Brea tar pits on the middle day and that was key to enjoying our final day at the parks.
If you're staying close to DL, you might also consider ducking out for an hour or two in the early afternoon to rest/nap/hit the pool.
Another thing to consider is at those ages, your kids will probably get just as much out of one day at the parks as two days in terms of memories and stories. So if the adults aren't that big on it you could just do one day at whichever park has more rides that meet their interests. No need to tell the kids they're missing anything, they can figure that out for themselves when you go back again in five or ten years!

Quoted from xsvtoys:

They’re coming to Huntington Beach so that’s about a 30 minute ride to DL give or take. Also, there is a big beachy beach here as well which isn’t too bad in June. Trips to LA to hit the tar pits and such would consume pretty much a whole day.

Quoted from naf_llabnip:

Great idea to split a day in between the parks. We are staying in Huntington Beach (love it) on vacation and recently did a Tuesday at Disneyland and then a Thursday at Magic Mountain (no kids, just us). Absolutely get the Genie Plus and be sure to reserve your days way in advance. We spent 8 hours at Disney and rode 12 rides, everything we wanted and Space Mountain twice. Also paid the extra to get a timeslot for Rise of the Resistance, which was a true goosebump inducing attraction for me. Magic Mountain not good for younger kids, but the day we went the park was completely empty and no more than a 5 minute wait for the most popular rides (rode 14 rides in 5 hours and even took our time with lunch). Anyway, I think your kiddos will want to see each Disney Park, split up those days as they can be exhausting. And be sure to ride all of the Star Wars rides for yourself (and kids)!