You'll find Suzhou cuisine a bit on the sweet side. Songhelou, mentioned by another poster, is a historic restaurant that created the notorious "squirrel fish" dish (松鼠桂鱼 - song shu gui yu). Suzhou is also the home of my favorite river eel preparation, the heavenly xiang you shan hu (响油鳝糊).
Sorry did not see this until today, hope not too late for your purposes.
Spent 4 days in Suzhou in March, love the city, hope you enjoy it as well.
For Suzhou style food:
The restaurants near Guanqianjie (the main pedestrian mall) are by and large very good. My favorite is the Wang Si - their beggar's chicken (available without special order) is excellent as is their pine nut Dong Po pork shoulder, less cloying than most - and they have a sliced lotus root in tangerine juice appetizer which is one of my favorite things to eat, period - so refreshing (trying to perfect it in NYC, not quite there yet). If this is a consideration, they have an English menu and one of the younger waitresses there is a sweetie. Have had good meals at the Songhelou as well.
For dian xin in an attractive and quiet setting:
Excellent dim sum (dian xin) at the restaurant in the Sheraton Suzhou, all you can eat, RMB 88 pp - everything freshly prepared, the absolute best har gow ever (shrimp and scallop).