One day in Shanhai. You can do a lot of things in one day but in Shanghai there are a lot of things to do. How how should you prioritise and plan so you see the best of Shanghai in this short time?
Assuming you are arriving by air to Pudong International airport, take the maglev train then at the terminus, switch to the subway line 2 into the city centre. The maglev is a little bit more expensive than taking the subway the whole way, but the maglev is one of the city’s tourist attractions, so why not.
Get off at Lujiazui station (line 2). This is near Oriental Pearl tower, Jinmao tower, WFC tower and the new Shanghai tower - some of the tallest buildings in the world. I wouldn’t bother going up any of them, but admire them from below.
Walk over to Binjiang park, just west of the towers and on the Huangpu river water front. Enjoy the view.
Walk south along the water front about half a mile and you will find a small ferry that can take you across the river to the famous Bund on the west bank. Walk northwards along the Bund waterfront enjoying the view till you reach Nanjing Road.
Nanjing Road is the main shopping area in Shanghai. If you want to do some shopping spend some time here.
If the weather isn’t so good, continue up Nanjing Road to Xizang Middle Street and turn left into People’s Park (People’s Square). Here you will find Shanghai museum. This free museum is excellent quality.
If the weather is good, and you have been making a good pace, or you don’t care for museums, from Nanjing East Road, walk down Henan Middle Road to Yuyuan Gardens. (You can take the subway but it is only one stop so hardly worth it.) Near here you will find the Shanghai City Temple and the surrounding tourist shopping area as well as the traditional Chinese gardens of Yuyuan and an interesting Tea house in the middle of a small lake just outside the gardens. You should find enough here to entertain yourself for a few hours.
Returning to the airport, simply take line 2 on the subway all the way to Pudong Airport. Expect the journey back to the airport to take about 2 hours. You can save about half an hour by using the Maglev again or you could take a taxi depending on the time of day and level of traffic.
The above is just about manageable in the time you have available, if you don’t dilly dally, but you might adjust things as the day goes on depending on your level of interest in certain places. Generally, I’d suggest you look at attractions that are situated along, or near to, subway line 2. This allows you the fastest entry and exit, so you don’t waste too much time in transit.