A flight via SYD will give you access to the F lounge

As will a direct flight on Jetstar ex-MEL. And at leisure, based on time you chose to arrive at the airport, not at the whim of connection buses.
And if you're looking at Jetstar, at anything other than the Flex fare level, you will not earn any FF points, so I would also consider going on Thai - bearing in mind that on Jetstar IFE, food, drinks, blankets all cost extra (as well as luggage if you have any). Also Thai have better seat pitch than either QF or Jetstar.