The subway stations at both PVG and SHA are incredibly conveniently located (SHA-T1 excepted a little bit), and trains run every 2-3 minutes (i.e. much less wait time than the taxi queues). Furthermore, the maximum price you will pay is Y8 pp to reach any station within the 800 km system.

But, I want to highlight two points about the subway drill:
1. Some of the transfers entail 1000 meter walks
2. After you reach the station closest to your destination, you might want a taxi to go the last mile, and getting one might not be easy
-while the cars certainly exist, actually linking up with your car requires figuring out a good pick-up location

The other option is a taxi directly from the airport to your destination. Anyone who is concerned about point 2 (last mile) should avail of this because, while you will need to wait in the queue, your are pretty much guarantied a nonstop journey to your hotel's front door, and the price will be no more than 200 from PVG or 80 from SHA.

By the time you are ready to leave town, you might have figured out that People's Square, Exit 20 is a short walk away, that is doable even with heavy luggage.