pinaka exciting is for you to climb the Harbour Bridge. The Syndey Bridge climb is among the city's biggest tourist drawer. You get a spectacular view of the city, opera house, and darling harbour.
Also go and visit the Sydney Aquarium. See a movie in the IMAX cinema. Stroll along the circular quay. You can schedule this city tour during the weekdays. Als go to Wonderland theme park. And if the weather is good, skinny dipping at Bondai Beach.
During the weekend, go visit the 3 sisters and bushwalking at...i forgot the name of the place.
I havent been to gold coast but they say the place is awesome.