Quick note about the Canadian vs American side of Niagra falls, US side is like a state park where you can walk down and stuff and generally isn't very developed, Canadian side is kinda like Disneyland, Maids of the Mist ride out of there, etc. Either way you won't need the day unless you're gonna do the other stuff around the area, like I think there's a gorge you can ride a thing across and whatnot.