The high-speed railway network is very well connected. I’d only recommend flying for longer distances where it can save a significant amount of time.
As for MO Pudong, I had no issues with the location. The service, particularly housekeeping, was excellent, as were the rooms and the views. The pricing is also very good and often includes a third-night-free offer.
I’d recommend using ride share for getting around as it’s affordable, efficient, and far more convenient than public transport like buses or the subway.
You’ll also find plenty of private guides available for half day or full day tours, or specific attractions. Viator is a great place to start your search.