The St. Regis is pretty much right next to the famous Silk Market (the new 5-story building now). They have everything and anything knock-off wise that you could want. A great place to do some gift shopping for sure. The Great Wall Sheraton is further from the city center and not as nice a hotel. When I looked at some dates for next month, the St. Regis was actually cheaper on certain nights (like weekends). Having stayed at both, I'd defintely opt for the St. Regis, for the great location and especially for the proximity to the Silk Market for your gift buying.
The Grand Hyatt is also a nice hotel (on the same level as St. Regis), but expect to get denied for a Diamond Upgrade (and Lounge access) during Sept, a very busy month for them.......