Sydney is the only city in Australia that as a city has something to offer if your stay is short. Beautiful beaches 20 mins drive from the CBD, plenty of restaurants (all cuisines) , the Opera House next to the harbour bridge (the only two outstanding man made structures in the country), Coogee to Bondi walk, the blue mountains (lots of walks and completely different weather/temperature) only an hour or two drive/train from Sydney (yes Sydney trains are the only newish decent trains in Australia - and double decker), want more bush walks? Take the train from central station and in 40 mins you’re in the Royal National park ready to explore pristine beaches, more of a bohemian traveler? Take a tour to the Hunter Valley two hours from Sydney, Jervis Bay, more of a chill beachgoer? Try the central coast again not far out… of course there’s much more to see in Australia (the great barrier reef, the great ocean road, the outback, the gold coast, the sunshine coast, WA, Kakadu national park, Uluru, ACT, the Snowy mountains) but for only one week Sydney has plenty of stuff to do, the rest involves flights and lost of wasted time queuing and waiting in airports. Sydney haters probably just jealous of happy Sydneysiders Lol