We quickly hopped on a train to downtown and dropped off our bags using a BagBnb near Martin Place. We actually would only be in Sydney for the day (our overnight flight having arrived early in the morning) before catching an evening flight to Brisbane. We'll be back to Sydney later on our trip, but we wanted to make the most of this long layover (which technically wasn't a layover: our flight to Brisbane was on an entirely different domestic carrier and had been booked separately, which is why we couldn't cut it close on the connection)