wdric,
I reckon best bet for the family is to go to Cairns. You kite at Yorkeys Knob which is as good as anywhere in North Queensland ie choppy brown water, but the beaches are long and clean ie (good for the Family) and Cairns has absolutely heaps to do. Even if you get 2 weeks without wind, there is enough activities to go on with the family to fill in a couple of weeks. Accomodation is also reasonably priced and it's warm and sunny (and windy).
You keep your aussie dollars in Oz and support aussies with jobs and the exchange rate is excellent 1:1.

Other benefits are: this is the land where Bundagerg Rum is made and drank in large quantities

. There are heaps of back packing euro chickys to subtly glance sideways at, and if the kids give you the willies, there's always the croc sanctuary

.
You can get stuff from Kiterite at Yorkeys from Chris (nice bloke).
All in all not a bad place to hang for a few weeks, besides you can always pop up to Port Douglas for a change of scenery. Nothing to do in PD for the fam apart from window shop at the outrageously priced items or eat in the outrageously priced restaurants and stay in the outrageously priced accomodation.
I'm not saying that Cairns is the best kiting you'll ever do, but at least the fam will have loads of options so they wont be hassling you and begrudging the fact that you will be having fun on the water nearly everyday.
Good luck and have fun.