I've stayed extensively in Hawaii on and off about 150 nights/yr for the past 7 years. You have many more choices now than several years ago.
I'll be brief. Please don't play to vacation on the island of O'ahu for two weeks in a row. You'll need to spend on inter-island airfare, but please go to at least one other island with your family. I'd recommend Maui and the Big Island (if you can do three islands).
First, you get 5 nights for the price of 4 with your points. Book stays in increments of 5 nights (for example, two stays of 5 nights each on O'ahu and Maui and then 3 nights on the Big Island).
For some point savings, there are now Courtyard Marriots on Kauai (near Lihue), O'ahu (Honolulu), and in Kailua-Kona. The Marriott Waikiki offers excellent customer service and readily upgrades platinum members. I would recommend their hotel outright except for the shower/tub bathrooms. The Waikiki Edition is no longer a Marriott property, so you can't use your points there (and the service was lousy anyway). You'll enjoy the JW Marriott in Ko'Olina with all the marble and giant fish ponds. Spendy food out there though by comparison, but then again, the Disney Report is next door and your kids might beat you into submission wanting Mickey Mouse instead of JW Marriott Sr. LOL
Options for Maui include the Waikoloa Beach Marriott and the Ritz (not a point saver!) as well as a timeshare location (there's also a timeshare / Marriott Vacations location on O'ahu in Ko'Olina).
Big Island properties include the Waikoloa Beach Marriott and the Courtyard King Kamehameha.
Anyway, that's all off the top of my head. There are also several properties on Kauai, but I don't recommend you go there with the family. Enjoy your trip and I hope this commentary has been helpful.
Two weeks is a long time to vacation, I stayed at the Ko Olina JW Marriott back in September and I loved it. I got upgraded to Ocean view suite (Im a platinum) and it was nicer than the standard rooms in the actual hotel. I was there on opening day of the Disney resort and I agree that if you have children they will make you buy a few nights there as the pool area is AMAZING! They have water tube ride, an aquarium in which you can scuba just to name a few off the top. The man made ponds are great, however the other side of the property gives you an almost virgen view of the giant waves as they crash down on the rock. I woke up everymorning to the music of the waves just outside my balcony.
Best tip eat at "Just Tacos" up the street and have a Michelada & a fish ceviche. Almost better than those back home and I live here in California.