Regent Beijing is across the street from the Peninsula and about half the price for pretty much the same thing. Service is not like Thailand in China even at these luxury type properties so I’d avoid the $500-1000 a night places and stay in upper tier chain properties.

Shangri La Shanghai in the River View wing, club floor, with river view is better for a first timer than Mandarin which isn’t in a great location. In your situation I’d stay there or newly renovated Hyatt on the Bund rather than Mandarin. The Regent on the bund in Shanghai also looks nice although I’ve never stayed there.

I’d stay at Hyatt or Shangri La in Hangzhou rather than the ultra fancy places. A unique treat would be to stay at one of the Naked resorts around the Shanghai area, those are truly unique.

Enjoy the trip, China was my home for 15+ years and it’s a great place to visit!