Tasmanians coming out of the woodwork!
Putting my North Queensland hat on (lived there through 2005), a suggestion on the Cairns area would be for Port Douglas or Palm Cove, where there are some good accommodation choices, and the great "rainforest and reef" experience that kids and family should enjoy.

After all, even Bill Clinton has been a past visitor.......

Hope you and the family have a great visit..... it's fairly hard to go wrong whatever you end up choosing to see here!