The best one way fare we could get from Australia to Panama at this time of the year, happened to be with Air China via the US where we get on an American carrier to Panama. En route we are looking forward to seeing in the New Year, as well as a few days of winter sightseeing in Beijing where we hope to find the top scenic spots underpopulated in winter. A few days in San Francisco before Panama City should also be pretty good since we'll be catching up with a friend, plus SF has as great a foodie reputation as Melbourne.
So, not much left to do having got all the pre-travel immunisations, travel gear, and applied for ESTAs and China visas.