Niagara Falls is a scenic part of the border between Canada and New York State in the US, and from Niagara Falls Airport you will have direct links to both. The Falls themselves have plenty of entertainment to keep you occupied, and you can even ride into the thick of The Falls on the Maid of the Mist boat. There are three main waterfalls across Niagara Falls, so hire a car from Niagara Falls Airport to navigate around the wider area, as well as state parks, the Skylon Tower for panoramic views of the area and the Whirlpool Aero Car which takes you over the Niagara Whirlpool if you visit the Canadian side of The Falls.
Should you rent a car from Niagara Falls Airport, there are a couple of bigger cities to visit nearby. Buffalo is around a half an hour drive from the pick-up location. There's a zoo, plenty of museums and plenty of restaurants to explore. Make sure you try the native Buffalo Wings of the area, although pretty much every cuisine is available in the city. In the opposite direction, the New York coastline is another half an hour drive away, there are a couple of state parks to explore in this area, as well as Old Fort Niagara which now serves as a history experience with regular re-enactments and the hosting of occasional special events.