When I was in Bangkok 10 years ago , at the time there was the one and only rooftop bar, which I believe was later featured in a famous Hollywood movie.
But as time passed, more and more new rooftop locations have opened and you are free to choose where to go.
I looked up which rooftop bars have recently opened and Spectrum Lounge and Bar fitted the bill perfectly. It is part of the newly opened Hyatt Regency Bangkok Sukhumvit Hotel and boy, it is spectacular!
The bar has two floors and at the time of the visit, the second floor was not accessible due to private event. But fear not, the floor below also offered fantastic views and sumptuous sitting areas.