Was talking about Sapporo in a different thread...
There's plenty that Sapporo can offer: Odori Park, Moerenuma Park, a walk in the Hokkaido University campus, Asaichi morning market, Shiroi Koibito Park, Sapporo Beer Factory Tour, Okurayama Ski Jump ramp, Shopping near Sapporo Station, Nightlife in Susukino, etc.
Be sure to eat Sapporo food: Ramen, Jingisukan (lamb grill/yakiniku), Seafood (how about kaisendon, sashimi on bowl of rice?), Butadon (pork rice bowl)
I was there in the dead of winter and just missed the Ice festival - definitely one to check out!