I also use Entertainment books for good travel deals on food accomodation and attractions.
Entertainment books can save lots and lots of dollars and can be good for the travel budget.

Plenty of choice; museums, galleries, restaurants, shops and more.
There are a wealth of restaurants and it depends on your tastes in food!
I look up What’s On sites for current events and places to see and things to do.

How disappointing your show was cancelled! I’m sure you’ll still have fun though. Personally, I would head to Sydney harbour and have a good wander around. I love being by the water

Bondi Beach isn’t too far away from the CBD, Icebergs and lots of restaurants. Google Time Out Sydney, will give you an idea of what else is happening and close to you. Dinner, drinks, wandering around markets at Paddington (Saturday)and Bondi Beach (Sunday) can be a lot of fun, especially after leisurely breakfast. Have a lovely time.

Oh. If you like walking, we did this walk different times. It’s gorgeous.
The Spit to Manly walk. https://www.sydneycoastwalks.com.au/spit-to-manly-walk/

Luna Park is free if you don’t go on the rides at all. You can get tickets that you can do several trips on the buses and trains. No kids to watch and supervise at all. Great for sightseeing if want to have a good lock around. I don’t know about hotels/motels. We found some good eating places at Circular Quays. Some catered for special diets too. It really depends on your interests. If you want to go for a casual walk there is a big area near the Central Railway Station on the opposite of the road.

Harbour Cruise; Taronga Zoo; Climb the Harbour Bridge; or visit one of the Outdoor Cinemas.

Howw about cruise with lunch ?

Take the ferry and go to Manly Beach. It’s a beautiful area, and the ferry is quite exciting. If you want to have a nice drink with amazing chocolates, go to Lindt Cafe’ in Martin Place. It was my favourite place when I lived there. I enjoyed Taronga Zoo, the Luna Park… I know they’ve opened Madame Tussaud since I left. I’ve never been there but I heard is quite nice.
Crossing the Harbour Bridge while walking is also nice. And visit The Rocks. There are a lot of little shops, cafes and restaurants also there.
Have a wonderful time. I hope the smog will be less by the time you are there.

Go to circular Quay and take a ferry around Sydney harbour. Also visit the famous Seafood and chips restaurant at the Quay (Doyles? ) I think.