I'm arriving a couple of days before you, i've booked 6 days in Bunk backpackers which is located in fortitude valley not far from central Brisbane i believe. I had a look through quite a few and that one seemed to be quite well recommended. It is more of a party hostel though so it depends what you're after, I decided to stay there as it looked the most sociable as i'm travelling alone. Chances are you're gonna want somewhere quieter to sleep off the jet lag, if so there are ones that are more suitable for a decent night sleep than for party atmosphere. check hostelbookers.com or hostelworld.com usually have all the info you need.