Here are some walking tours to choose from:
Puxi Bund Building Tour
This walk gives you a quick introduction to the famous buildings along the Puxi side of Shanghai's Bund. This is a pleasant walk to do during the daytime or at night and can be combined with meals and drinks as many of the buildings have fantastic (but high-end) restaurants with terraces and bars.
Fuxing Road Walking & Shopping Tour
This leisurely walk takes you on a stroll down the western part of Fuxing Road. The tour highlights the shopping along the street but there are also lots of restaurants, cafes a wine bar and a micro-brewery that are worth a stop if you're hungry or thirsty.
Shaoxing Road - Taikang Road Walking Tour
This tour is nice, especially if you have kids with you, as there's a park stop on Shaoxing Road and plenty of gelato on Taikang Road (in the alleys) to help them along. Shaoxing Road is one of my favorites in the French Concession and Taikang Road is full of alleys to wander through.
Honkou Jewish Quarter Walking Tour
This historic tour takes you through the Jewish Ghetto north of the Bund. Shanghai's Honkou district was home to a thriving Jewish community pre-WWII as thousands escaped Nazi Germany to come to Shanghai where no visas or passports were required at the time. After the Japanese invaded Shanghai, under pressure from Germany, the Jews were interned in the ghetto until Allied Liberation. This walking tour lets you see some of Shanghai's fascinating - but quickly vanishing - history as old buildings get demolished to make way for high rises.