Hi, for the major places of interest in Shanghai, one day will be enough for you to visit, such as the Shanghai Museum, Yuyuan Garden, the Oriental Pearl TV Tower, the Huangpu River cruise tour, etc. However, the Bund and Nanjing Road are also the good places for shopping and walking. For the other day, you may take a side trip to Suzhou or a water town around Shanghai. You can also check the following web for more suggestions:
https://www.travelchinaguide.com/cityguides/shanghai.htm