My impression is that most people overthink the hotel choice, especially in a city like Shanghai that has so many extraordinary options. We stayed at the Pen in 2012 and absolutely loved it...but we also visited for meals/drinks (as we always like to do) other top hotels in the city, including the Park Hyatt (which we also loved on the Pudong), the RC Pudong (which is beautiful but not as much our style), the Waldforf Astoria (majestic, and even more formal than the Pen IMO), the Fairmont Peace (fantastic lobby), and the Puli (which was spectacular as well). I honestly think all are amazing hotels--it comes down to which might be better located for your purposes, which might offer the best value for the room type you prefer, and which design motif you prefer. I don't think you can go wrong, to be honest, with choices such as these. We're parsing these choices as if there are substantial differences between them in how wonderful they are--and the differences are trivial in every way but location, style and perhaps the price you can get at certain dates.

If we were to return to Shanghai (which turns out to have been my favorite big city in China, even surpassing HK), we'd opt for the Pen again after having such an amazing stay (its Grand Deluxe Riverfront Suite is without question the most amazing urban suite we've ever experienced) if we wanted to be on the Bund. We also would strongly consider the PH (if we wanted to be in Pudong or earn/use Hyatt points) and Puli (if we wanted to be more in the downtown) if the rates were right. We'd also want to check out the MO. We've been too disappointed by the FSs we've stayed at and visited recently, but we'd likely check them out, too, if time allowed. Talk about spoiled for choice!