Lots of good tips already. Here are some of mine:
– Visit Qing Cheng Shan. Ben already mentioned this, but you can take the new train there in 30 minutes and it’s right near Dujiang Yan. There was some damage to Qing Cheng Shan in the 2008 quake but it’s still beautiful and dotted with temples.
– DVD shopping / Computer City. This one never fails to stun visitors. The size and amount of activity in the computer buildings at Renmin Nanlu and First Ring Road is pretty nuts. When people offer DVD’s for sale, let them take you to the secret DVD dens. It’s an adventure.
– People’s Park (Renmin Gongyuan). Sunday’s are great, the park will be filled with people and there’s live music, dancing, kids flying kites, tea houses, and lots of activity. Old men with song birds in cages, etc. Good times.