The Queen Victoria Market is always a fun and different place to visit. It is located in the CBD so it's easy to get there using the Free Trams. If you go on Sundays, breakfast and brunch are amazing and very lively with all the people, music and food. You can try a great variety of food from different places of the world. I can highly recommend buying Spicy Salami and spices.
Don't miss exploring all the random clothing and things stores. I'm sure you'll find something you like. The souveniers are also great and they have the best prices I've seen in the country. I got two sweaters that soon became my favorite thing for chilly days. They are ideal for a cozy day at home or a casual walk in the city.
Check the itinerary before going to make sure it's open when you're available!