I think this is definitely a doable wish, just takes some time and money. You can find some reasonable airfares LAX - HNL. I usually fly Hawaiian and see great deals in Feb and March. May can have good prices, too. Airfares will be higher around Easter and spring break time. Rates to Hawaii will also drop in Sept and October. My favorite times to visit are May, Sept and October. Winter holiday rates can be very high. As it turn out these are great months to visit DLR, too. We usually have good weather in May ( even though we had rain today) , Sept and October and crowd sizes at the parks are reasonable.
For a first visit to DLR I would spend atleast 3 days. Stay on site, if possible, but there are many less expensive hotels nearby than are walking distance to the parks. Be sure and buy park hopper tickets because the two parks are right across a "courtyard" from each other. The "new" California Adventure is wonderful. The changes they made to the park have made such a difference. I now often go and spend the entire day at CA. It used to be a 3 or 4 hour park.
Depending on the amount of time (vacation) you have, don't island hop. Just go and spend 5-6 days (min) on one island. Aulani is beautiful BUT it is not in a great location.i would not recommend it be your home base on Oahu. I love Waikiki and you can find nice beachfront hotels for a more reasonable price. Great bus system on Oahu, but car rentals are very reasonable. The problem is parking and most Waikiki hotels charge about $30 or more a day for parking.
Lots to think about, but sounds like an awesome vacation. Have a great time.