I haven't done the climb myself (VERY afraid of heights!!)...but my Dad who suffers badly from heights also did the climb earlier this year and said it was fantastic. They hook you up with safety ropes and the whole thing was so well controlled he said he wasn't afraid in the slightest.

If you decide to go ahead book an early evening climb so you can watch the sun set and the city light up...but book early as this is the most popular time.

As for the weather...Sydney will by far be your coolest climate in Oz and given that you are spending so much time in Queensland with plenty of swimming I wouldn't be too concerned. Last March was very warm and we certainly swam right uo to the end of the month before we came home to Hong Kong. March in Sydney if you are lucky is mostly warm days and cool nights.

Even if it's too cool to swim, the beaches are generally long, clean and great for a walk.

Kate