ey, highly suggested you go to Wang fu jing Snack Street. There you can find almost all the distinctive local food.
Or you can go to these two restaurants:
1. Xiang Yu Xiang Yuan (湘与香缘): no. 88, WFJ Street.
2. Huo Lu Huo (火炉火): no. 138, APM Shopping Center, WFJ Street.
The best time to move around: both day time and night time are ok. You will have different views and different feelings about the city in the street.