Hualalai is great for kids, if your TA can ensure your stay does not coincide with a corporate event or very crowded holiday crowd -- any holiday.

Hawaii is lovely and if you've never been that could be reason go. I gather you are accustomed to tropical locales so some of the charm may not be apparent. Best resort experience is FS Manele Bay. I think there is a deal if you visit both locations. Beach at Manele Bay is very good.

Avoid Oahu if possible; there are direct/non-stop flights to Big Island (depending on outbound airport).

I am not now a Hawaii fan due to the paucity/lack of genuine 5-star luxury but loved my first visit when we stayed at the Lodge at Koele, Manele Bay (not then FS) and Hana Maui on Maui.

I think the luau experience is tacky (plus lines for buffet) and very likely inauthentic but kids adore it.