I recently visited Sydney with my family (2 adults and 4 small children) and we had a memorable 5 day trip.
Here is a summary of our trip:
Day 1 - landed in SYD after a red-eye flight from Kuala Lumpur. My 7 yr old son had developed infection in his finger so I took him to medical facility in the airport and then we headed to our hostel - YHA at the harbor. We spent rest of the day exploring rocks.
Day 2 - We bought Taronga zoo pass from Circular Quay and took ferry to the zoo. The zoo is good but as not good as other zoos that have been to. The best part was watching two tigers horsing around. The zoo has amazing harbor views though.
Day 3 - Took 555 bus from circular quay to Darling Harbour. Kids enjoyed Sydney Aquarium but my 1 year old threw a major tantrum so we had to leave prematurely. Next we went to Australian Maritime museum. Since it was Thursday, the entrance was free. The museum is very good and our kids had lot of fun there. Chinese friendship gardens didn't look interesting for kids so we skipped and instead let kids enjoy the adjacent playground.
Day 4 - Walked to Sydney opera house and enjoyed a stroll in the botanical gardens. After lunch, we took ferry to Manly. Kids had fun playing in the beach and chasing the sea gulls. We had pizza and kebabs on the beach before heading back to Circular Quay.
Day 5 - Took train to Blue Mountains. We had purchased a blue mountain explorer link tickets that covered both the train ride to Katoomba as well explorer bus in Katoomba. After visiting the three sisters and other places in the explorer bus, we had fish & chips in one of the local eateries in Katoomba main street. The 2 hour train ride was very enjoyable considering the train was not very full.
Day 6 - Took morning flight back to Kuala Lumpur.
I would say the best part of our trip was interacting with local Sydney residents. I found people to be very friendly and helpful. On several occassions, we had people helping us with directions as soon as they realized we were lost.
I also want to thank the forumites with their helpful suggestions such as where to buy groceries near the rocks and which places to visit.
Few tips for future visitors:
1. Stay at YHA hostel if you want affordable place with easy access to tourist spots. Book family room if you have small kids.
2. If staying in the rocks area use 555 free bus if possible to get around the city center.
3. Buy Sydney Aquarium passes from their online website. It is much cheaper than buying at the door.
4. Do not feed seagulls at Manyl beach...before you know it, you will have 100 seagulls swarming you!!!