Bring a theme park fan.. In my one day in Hong Kong, I visited Disneyland, it was cool-ish and misting/rain, the park was a ghost town and I was able to do everything (some things 6 or 7 times!) within a few hours and then left to explore the actual city.
I spent 5 days in Singapore so I checked out the Universal Studios park there, unlike at Disney, it was incredibly busy and pretty subpar operations. I also visited the delightfully odd Haw Par Villa for maybe an hour of just... experiencing. Seeing the Merlion was a must for me. And also checking out Marina Bay Sands (that I was lucky enough to stay at!). Also spent a half day walking around the Gardens by the Bay, while you can go for free, I did do two of the pay-for areas, the giant indoor waterfall and the sky tree walk way. Wish I had gone back to see the area at night but I was so tired / jet lagged.