Hi, based on past experience I would not book standby within USA. The flight looks great but anyone can turn up hours early for their booked flight and check in for a earlier flight. They get priority over you. Had flights LAS- HNL. Told to fly to LA. No flights. Drove to LA. No flights. Overnight.
Internal flights are often not that expensive. Of course holiday period will differ. Good luck.
I'm assuming you are booking Staff for cruises? Great last minute deals. You also have the option of removing or reducing the gratuities if you think it is too much. It is very expensive by the time you convert to $AUD, especially now with the low exchange rate.