This year January my husband & I took a 12 days cruise from Sydney to New Zealand. We added 3 nights each pre & post cruise stay in Sydney. Sydney is very easy to get around by foot, underground trains & taxi.
On our pre cruise we stayed in the central business district (CBD) Hyde Park area. We did the free Self Guided Sydney Walking tour to top Sydney must see landmarks (found in internet). At Sydney Opera House we took a guided tour inside, bought our tickets at the Opera House. We saw many Hop on hop off double decks tour buses around town but we didn't take it.
On our post cruise we stayed at Darling Harbor where very easy walked to many restaurants, shops & China Town. Our hotel concierge booked our tours included guided Blue Mountain/Scenic World/Jenolan Cave tour, Zoo, Bondi beach, and prices were good as online tours from Viator. I’m sure Marriott hotel concierge can help you!
We used our Costco Citi Bank Visa card paid for everything including taxis, restaurants, tours, shops & etc. There is no foreign transaction fees on charges & still get reward. On our Visa statement showed reasonable currency exchange rate. We did exchanged $100 US at the airport, it was the worst exchange rate plus they charged a service fee. There were many currency exchange places around the city with better exchange rate & no fee. We did not use ATM.
By the way, in Australia you don’t have to tip! But you can if you want to. Also no sales tax add to your shopping, foods, restaurants too!