I liked Shanghai best. It has more energy than NYC and more style than London, Paris or Miami.
Beijing is a cold, harsh, rough place where the people are stoic and unfeeling. Hanoi is a dynamic unusual place, but it's just so goddam poor. Singapore is DisneyWorld, boring after about 10 minutes. (SingaBORE).
Shanghai is amazing, I could live there.
The hottest chicks were the flight attendants on Singapore airlines. Some attractive expats in Shanghai, and a lot of more exotic looking women in Singapore.