Agree re. the Bund at night. Amazing.
There's a huge bootleg market in one of the subway stations. I think it's near the science center or science museum or something. It's worth seeing even if you don't buy anything. Basically, all the designer stuff you could ever want, but knock-off (likely made in the same place as the real stuff). I got a ton of cufflinks and a nice Bali bag from there. Negotiate the #### out of things. If the stand you go to won't take your lowball offer, walk out, go 5 shops down, and try again. You can usually get stuff for easily 1/3 of what they start asking. I got some decent Tiffany knock-off cufflinks, and some pretty nice ties there too. They sell sunglasses, jackets, shirts, shoes, bags, scarves, most anything designer.
Some of the historic gardens are pretty cool too.