For HK:

One cheap self tour worth doing when you have time is to ride the front upper seats on the tram from east terminus to west terminus.

You will get the feel of old neighbourhoods, modern ones, ones under transition and the Central business district.

The other is a tram ride up the peak late afternoon so you can see the city from daylight through dusk to night. One needs to plan this for a day with clear weather and visibility.

Macau is a day trip with many food stops. Certain Cantonese food/snack traditions were better retained under Portuguese rule than British rule.