November's a great time to travel - it's not too hot, and most of the days are fine.
In Sydney I guess all the typical tourist spots - the opera house (free), climbing the harbour bridge (not free!), a ferry to Tooronga Park Zoo, perhaps.
The reef's further out, and further north, than most overseas visitors realise. In fact, although they have probably already heard this, most visitors underestimate the size of the country, and think it'll be faster travelling than it is.
If that makes any sense at all! I think I may come back and repost after I've had some sleep