2 day PH IMHO. It's rare that I would EVER choose that over 3 days in the parks, but I recently got back from Hawaii myself and OMG we were so tired. (Admittedly it was a red-eye flight, so totally not the same as yours!) My thinking:
-Time Change: the time change is 3 hours. 6pm will be 3pm to you and your fam so- win on Sat night!
But this means that if the parks open at 8am on Sunday it will feel like 5am to you and your crew, and that doesn't count time to wake up and get to the parks. Only having 2 days I'm sure you'd want to be there at opening.
-Travel Fatigue: how does your group do traveling? We get exhausted, we're tall people and flights are very uncomfortable for us so flying itself is a tiring experience even if it's just a 5 hour flight. Not everyone is like that though! I have seen some very preppy people at the end of those flights who could totally get of the plane and go on to conquer
Disneyland. I hate them. But that's my jealousy speaking

-Arriving later than expected on Sat: what if this happens? are you ok with the idea of getting in a couple hours later and only having a few hours in the park? I'm not saying it will happen but LAX is a freaking disaster of an airport, anything can and does happen so "just in case" plans are very important.
You could always buy your tickets on arrival to Disneyland, you'll miss out on early purchase discounts but you will be able to more fully evaluate which ticket is right for you.
Have a wonderful vacation! Aulani + Disneyland sounds AMAZING!!