I've never flown with kids but I've flown home to Sydney on both QANTAS and Cathay and can't complain about either. I usually find the QANTAS flights cheaper than Cathay. Look for flights on
www.zuji.com.hk
For domestic airlines i've flown both virgin blue and Qantas and again no problem for these short haul flights.
http://www.virginblue.com.au/ http://www.qantas.com.au/regions/dyn/home
This Australian website
http://www.whereis.com/ has maps of Australian cities, towns and travel destinations with driving directions and traveller information.
Enjoy your trip!