Terracotta Warriors: The First Emperor and His Legacy finishes it run on 16 October 2011 so you still have time to visit it before the “end of run rush” comes in. It is at the Asian Civilizations Museum which is just a short walk from City Hall MRT. Lots of museums are around in the area anyway.
I went to the exhibition on a weekday with Avarielle! Plus, since it was a weekday, there were school students on an excursion to the museum.