How important is hotel location in Shanghai and Beijing? What is the
best location for walking around to sights and interesting shopping
(as opposed to skyscrapers and malls)?

We're taking a tour of China, and will be on our own for three days
each in Shanghai and Beijing on either end of the tour. The tour has
us in the Westin Beijing (Financial Street) and the St. Regis in
Pudong, Shanghai.

The question is whether to stay in these hotels on our own, or find
better locations. We like to go out and walk around, but if there's
excellent public transportation near the hotel, it might outweigh the
hassle of packing up and moving.