Gng to HK in sept with my 2.5 yo girl. Other than Disneyland and trick eye museum, where else would be suitable for us to bring her? Is baby chair commonly be found in restaurants? Couldn't remember when I went there few years back

Ocean Park! I prefer it to Disneyland and there are a number of rides suitable for kids. Visit their panda too. For restaurants, you might to buy those seat support for kids. They are like harness which you can put around the chair and your child. Check qoo10 for portable baby seats.