well, if you are going for the nice pools and playgrounds for kids, you don't really have to go to Macau. But if you are going to another city, it is great to explore (even with a 2-yr-old toddler).
1. The Ruins of St. Paul's is the signature spot of Macau. My son loves going up and down the stairs.
2. Venetians. would be great if they still have the gondola. my boy loved it, but not sure if they still have it now.
3. Great to go around the city as it is full of Portuguese culture and you just don't see this kind of colonial culture in HOng kOng.
4. The "Black Sand" Beach. As the name tells, the sand is black in color, and you just don't see this in Hong Kong.
5. Try the local and Portuguese food. Yum yum.
Explore the city as toddlers are curious too.