I just returned from Aulani and I am pro photog and might have some insight for you. First, all HI beaches are public property, so you shouldn't have an issue shooting family portraits there. You might want to use the lagoon next to Aulani if only because it will be quieter. Lots of wedding photographers were out on Aulani's beach area taking photos of wedding couples from the chapel, so I can't see the beach staff coming after you.
BUT, you do want to be careful because 1) Disney can control any pro photography on its property. Outside photographers have been hired by weddings to shoot on property, but I'm sure they have to go through Aulani to get permission, check insurance, and agree to Disney's terms and conditions. I'd bet that Disney wouldn't let a pro photog impede any walkway for more than a minute without official staff and such. 2) Disney staff will be vigilant to protect their guests' privacy and their copyrights. If you are shooting on the beach in front of Aulani (and being obvious that this is a 'photo shoot') and getting staff or guests uncomfortable in the background or such, you'll probably be shoo'd away. Any any use of Disney in pro photos for $$ is - actually - prohibited.
That being said, many Aulani guests have the $$ to have sweet cameras and love to take family pics and even night shots of the hotel. If your photog dresses the part of 'Uncle Jim' and doesn't be an ***, I'm sure he could follow you around the property and get some AWESOME shots. 1 camera, great lens, camera-mounted flash, no tripod, no flexi-fill. Heck, he'd probably look like me shooting my kids! But do whatever your photog is comfortable with. An uncomfortable photographer will get you mediocre photos.