Why don't you ask your GF to suggest since she's posted there? She should have quite a good idea (and up to date as well).
Anyway just came back from a 4 mth posting there myself so had a chance to run around a bit. Some suggestions:
1. Yu Yuan - If you're into old buildings. It's near Cheng Huang Miao as well so you can visit both places together.
2. Xin Tian Di - A kind of pub/restaurant street. Apparently quite a lot of regional celebrities like to go down there when they're around (think I saw A-Mei there) so can go there to people watch although it's kind of cold now to sit outside.
3. The Bund - Default tourist attraction. Most people prefer the view from Pudong side as opposed to the Puxi side. The buildings on the Puxi side are lit at night so it makes for a pretty good night scene although tripods are a must.
4. Pearl Tower - There's an observation deck someone on top (need to pay for entry) where you can supposedly get a pretty good view of the city (I haven't been up there myself).
5. Hangzhou - You can buy a train ticket from the Shanghai train station to get there (remember to ask for a soft seat or ruan zhuo), cost about RMB60+ to get there and RMB 50 + to get back I believe. 2 hour ride. Go there to see Xi Hu (westlake), Yue Fei Mu (Tomb of Yue Fei) some temples, towers, pagodas etc. Was only there for 1/2 a day so can't advise much. Oh and the Xi Hu itself was so damn misty I could barely see the opposite side.
6. Zhou Zhuang - More old buildings. You can buy a bus ticket from Shanghai Stadium I think. 2 hour ride again.
7. Su Zhou - Haven't been there myself but heard it's quite near to Zhou Zhuang. Also about 2 hours out.
8. Nanjing Bu Xing Jie - Nice view at night with lots of neon signs. Tripod would probably be helpful.
9. Lots of old buildings etc if you wander around on foot. It's pretty safe there I think. I used to wander around on foot with my camera during weekends. (P.S. I'm referring to PuXi here)
10. Shopping - Huai Hai Lu (upmarket), Xu Jia Hui (big shopping centers), Xiang Yang Lu (pasar malam, fake everything from Rolex to LV to Swatch), Yu Yuan district (loads of wholesale knick knacks) just to name a few. Btw, you can get some really cheap 2nd hand stuff there, think I saw a seagull going for RMB50 ~ $10. But there was so much fungus on the thing I swear the lens was alive.
Didn't have much problems with my camera as most of the time it was going from a warm room to a cold place (outside) instead of vice versa.
Weather there should be approaching 0 to sub 0 so good luck.
Other then that, just watch out for the army of beggers, flower seller girls (especially if you're with your GF), touts (at Xiang Yang Lu) and overly friendly ladies :bsmilie:
Hope this helps. Feel free to PM me if you need any more info.