Flight Finder Larissa is from Sydney, and she's put together a hit-list of lesser-known spots she thinks you should check out below. 

Chinatown - Sydney has plenty of incredible Asian food on offer, with Haymarket being the place for your dumpling or noodle fix. Here, you'll find tons of cheap Chinese, Malaysian, Thai, Vietnamese and Japanese restaurants. For an after-dinner stroll, walk around to the Chinese Garden of Friendship. 

Wendy Whitley's Secret Garden - This spot is an open secret among Sydneysiders, but not many tourists know to stop here. It's a hidden park on the north side of the Harbour Bridge, perfect for secluded picnics.

Walsh Bay - A personal favorite of mine! These wharves make up one of Sydney's main arts precincts (if you find a car that's been smashed with a massive rock, you're in the right place), but they're also a great harbor-side spot away from busy Circular Quay. And, you get to actually walk under the bridge on the way there, which makes for a waaay more impressive photo op. 

Finally, let's talk day trips. You can either go west to the Blue Mountains, south towards Wollongong, or north to the Hunter Valley. The beaches, coastal walks, ancient rock formations, vineyards you'll find along the way are really hard to beat. 

You can reach most of these areas by train (just factor in extra travel time, because they can be a little on the slow side), or you can organize your own tour.