Ningbo is a small town by Chinese standards, yet as a port of no small significance on national scale in China, Ningbo has for centuries been one of China's gateways to the rest of the world. This is evident from the fact that many international chains have established themselves here, and that many rich (expatriate) Ningbonese have invested their money in their native town. The atmosphere seems more "cosmopolitan" to me some other places I know in China. Ningbo also seems to have an energetic expat community, adding to the international feel.
Westerners will feel at home on the shopping streets and around Tianyi square, complete with fast food chains and Starbucks (for those in need of coffee). For the culture part, make sure you pay a visit to the beautiful Moon Lake (Yue Hu) and surrounding parks and pavilions. Ningbo also boasts a centuries old library building.
The bund area in the northern part of the town centre, on the north-easterly shore of the river confluence, boasts a history 20 years longer than that of its famous namesake in Shanghai. This area has been part of a European concession and now has been revamped in European style, complete with Western restaurants, a church and the local Irish pub, Shamrock.
For a weekend trip, Ningbo is perfect. The town is small enough for you to be able to see most interesting sites on foot. However, if you spend more time in Ningbo, you will soon want to venture farther afield to see what else is to see in Ningbo county and beyond, in Zhejiang province.
Interestingly, many sights are scattered around the old centre of town, and then many others are within a fair distance of Ningbo (30-60 minutes by car). This is probably because Ningbo town has expanded more significantly geographically only in fairly recent times, whereas the area itself has been settled for at least 7000 years.