Lived here for ten years now. Old Mill is a good stay. Down town is another great place to walk around at night. Great night life for a small town in the down town sector. There are a lot of great places to eat, Old Mill has Greg's Grill and Anthony's. Down town has The Blacksmith, McMinnemen's (sp?) and many more. Just walk around, you can't miss the dozen's of fancy smancy restaurants. As for shopping, Old Mill or down town are good places to stroll around in. Are you getting a theme here? Those are the two hot spots. There is a good running store called Foot Zone down town on Wall St. You can't miss it.
Cool stuff to see depends on what you are interested in. For just a couple of days, I'd say the Old Mill is good enough for now.
Enjoy your stay.