This is going beyond what you asked, but if you miss out or seem to be getting forced in to a shorter trip, you could also tag PEK, CTU or PVG on the end. These tend to have better availability. We stopped over in PEK in December 2013 - it's cold but you have the Great Wall almost to yourself, don't have to get up so early to see sunrise in Tiananmen, and it's less avios than HKG for a daytime flight with more time to experience F. Plus you don't need a visa for <72hrs so it's a low-hassle way to see a little of China.