South stradbroke island is all ill say, depending if camping is your thing or not. One side you have the surf, other side is the broadwater, just a short ferry ride/then cab ride into surfers etc for the night life.
And the best thing is its cheap as chips. When i went there with mates there was 10 of us and it cost us around the 130 bucks for accommodation and food, plus a bit of booze to share between the group.
Was great fun.