Actually, I was just in Shanghai and while it seemed filled with visitors from opther parts of China (especially this year for Expo), the crowds visably thinned out by October 6-7. More importantly, the hotels oriented toward foreigners and business travellers were somewhat empty and the rates were surprisingly good. Assuming that one flies directly into Shangahi and does not attempt a domestic flight in China or train travel before October 7, it's easy with good availability at excellent fares. My DTW-PVG was less than half full in both coach and business. Availability NRT-PVG also was good during this period.