I went to Jinli Street at night which i would think is probably the best time to go as the place is covered in Chinese lanterns and hanging lights from trees. Its a wonderland of souvenir shops, street entertainers, food vendors and bars all decked out in traditional Chinese architecture. Bustling tiny streets, quaint stone bridges and wooden walkways overlooking small ponds.
Even though its authenticity may be a little questionable-i hear it was created after the previous area was demolished- it is certainly a touristy haven, so don't forget to bring a camera!
Its certainly a popular place, so if crowds aren't your thing then you might want to rethink; but for me the amount of people there added to the general magical atmosphere of the place, without feeling surrounded.
As you walk around you encounter wave after wave of smells spewing from the kitchens of each small stall which display a different array of tasty barbecued critters on sticks! All this and they've even managed to squeeze in a Starbucks to boot!
If you have kids i would definitely bring them along but with your wallet as there will be plenty of toys they will want to buy! Prices are probably slightly higher because of the tourism element, but not ridiculous.
Its free entry as well and a fun experience, if you don't mind the artificial element.