visited oz back in feburary - it gets the big thumbs up from me. i spent my time in melbourne though. melbourne, in a sense reminds me of denver (architecture, the people, and layout of the city). people are very approachable and friendly, to me they were.
i went during the summer. didn't hit up many clubs, like to dance but wasn't too keen on going. i opted to look for festivals, markets, cafes/restaurants by the water with live music etc. i stumbled across a wednesday nite market at queen victorias. i will say this: fellas, if you are single, this is the move. women from all walks of life (also a good networking event). they were very approachable and interested in meeting interesting, cool people. so if that is you, again, this is move. also, the market had cuisines from all over the world.
for the most part, the women australia are very beautiful. most importantly, many are active, driven, and have keen interests and are interested in things outside of oz (all essential for me). i found myself in coffee shops/shops many of day friendly bantering with gregarious women for a lot longer than i had planned.
i didn't visit sydney because i had too much fun in melbourne (which i figured i would). i have heard a mixed bag about sydney. i'd still go just to get the touristy pictures - just wouldn't stay long.