What are you interested in? For such a long stay perhaps you could (also) visit some of the islands - a few have flights from Brisbane including Papua New Guinea, Solomon Islands, Nauru, Fiji, etc. NZ can also be cheap to get to from BNE with BI (Royal Brunei), EK (Emirates), DJ (Virgin Blue/Pacific Blue), NZ (Air NZ), QF (Qantas), JQ (Jetstar) all flying the route(s).