During the day you have an International shopping paradise, with many restaurants. Trendy international chain stores, including Apple, vie with top of the line designer boutiques for your attention. Down the block is a series of super expensive international designer clothing stores. Behind Sanlitun is a previous "bar" type street crammed with interesting and good quality restaurants. Across the street, but on the same side of the street, is the Yashow Clothing mart with bargain clothing rip-offs of all major designer brands. Yashow itself may require a separate trip to avoid sensory overload.
At night, the place swarms with trendy young foreigners out on the town. It's a very different, but still fun experience with people watching to the max.
Don't forget to sample one of the many good restaurants ranging from Vietnamese to Israeli to authentic Italian pizza.
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC.