Yep, that's correct, it is the only one with direct flights with a major airline ie Jetstar. You can however fly to other islands on small charter planes (more so in far nth QLD) and get heli-transfers to Hayman but that's a pricey island

Hamilton is a great family island with loads to do and various accommodation options. It's easy to day trip from Hamilton to other islands or the likes of Whitehaven Beach which is breath taking!

I'd highly recommend Hamilton for a family holiday. Enjoy!