PSA: Avoid RWS Sentosa when there is heavy rain. A lot of the 'sheltered' areas do not protect you from the rain.
1) Escalators going down to the casino lobby from the street level.
2) The 'sheltered' areas in front of Universal Studios entrance, until the shops to the side (Reese's, ice cream etc).
3) The seats at the casino lobby (just next to Harry Potter Visions of Magic).