Lots to do in Toronto but close to the HHOF is Rippley’s Aquarium. Depending on what aquariums you’ve seen it is a pretty good one. Next to that is the CN Tower, beautiful views of the city. There is also a skywalk there if you’re adventurous. If the Jays are in town catching a couple of innings at the Sky Dome (Rogers Centre) is a good way to kill some time, if the roof is open even better. That is all walking distance from HHOF. Beyond that Toronto has a world class museum, art gallery, science centre and zoo, numerous stage productions are often running in fantastic theatres and endless places to eat.

Niagara Falls is the most touristy place I’ve ever been. The falls are spectacular, taking the Horn Blower/Maid of the Mist tour is a must if you haven’t done it before and don’t plan to be back, it will get you so close to the power of Mother Nature it is amazing. Clifton Hill is full of kitschy fun.

Looks like you may be out of luck, their website says the following:

Children 14 and older are permitted before 8pm, and must be accompanied by an adult

Drop them an email to confirm 100% though.