The Buffalo Riverwalk now extends from northern Erie County to downtown Buffalo with a Canadian artery that intersects to the Peace Bridge and over  to the Canadian Niagara River Trail (remember your passport).  To get the map.

The directions here are from LaSalle Park which has access to the Riverwalk but there are a number of places you can access it.

You can walk, bicycle, bird watch, rollerblade, and fish and in the winter, ice fish. PLUS, there is an play area for younger kids.