I suggest you to Huaihai Rd and Sinan Rd if you like to see the houses build during the 1900s. Xitang(a small town near Shanghai) will be a great place to touch the living style thousands of years ago in Southern China. You would never regret if you go and see the morning and dark in Xitang. Xintiandi or Hengshan Rd is great to spend a night, for dozens of bars in it. Hope my answer is not to late:-) over 8 years ago
Got to the Bund, the old town, the Jade Buddha Temple, Huaihuai and Nanjing Lu (street) and to people square on a weekend, maybe you can see the marriage market...
And get up early, to see people practicing Tai Chi on the streets (or at the Bund)! about 8 years ago