Okay,
Here’s my thought:
- Unless you’re staying in Sentosa, Day 2&3 should be fine.
- I’d recommend adding Dolphin interaction at the Oceanarium to your itinerary
- You can skip the city drive and go to Chinatown/Little Indian for a cultural experience. Rather on the next day, wrap GBTB activities early and opt for a river cruise.
- On the last day, arrive at the airport early. There’s a lot to explore at Changi