As you point out, the problem of hot weathers like Singapore is that light frags will evaporate very fast, and the heat will make thicker and sweeter frags become too cloying.
Since you mention, vetiver is a fresh green material that works well in the heat - though it is typically green and dry, without sweetness. In addition to the Guerlain, in mainstream there's also Tom Ford Grey Vetiver and Lalique Encre Noire.
For something with a touch of sweetness, I'd suggest you try Kenzo Flower. It has a light melony note and is quite fresh, and despite the name, not very floral.