Where are you planning to stay?
If you are staying in Toronto - you might want to look into doing a day tour from your hotel. These tours include IMAX show, Maid of the Mist (boat to the base of the falls - a must do!) and sometimes lunch. It would take the pressure off driving the QEW (highway from Toronto to Niagara) which takes about 2 hours. (Sorry grinningghost - 1 hour is not possible from Toronto to Niagara!) In July traffic/construction can be terrible. Check with your hotel and they can direct you. Otherwise I would recommend at least one overnight at Niagara Falls. You can always stop at Niagara-on-the-Lake enroute. This is one of the priettiest areas in Niagara. You can then take the "scenic" drive into Niagara Falls, instead of the highway.
The Canadian side is much better for viewing, plus much more activity - parks, tours, and major "touristy" things to do.
Toronto - The Hockey Hall of Fame is right downtown. You can expect to be there about 3 hours. I haven't been there for a while but there are lots of interactive items to do which would really entertain your DS, especially if he is a Hockey Fan. All the trophies are displayed there as well. My favourite part is checking out the Stanley Cup! There is also a nice restaurant right at the HHofF called LeMarche. It's set up like a European Marketplace, it's fun and a unique way to dine.
There are also a lot of things to do in Toronto. If you are planning to go up the CN Tower (another must!), make sure you are there first thing as the line ups in the summer can be as much as a 2hr+ wait later in the day! My advise would be to do the CN Tower first thing, then walk over to the Hockey Hall of Fame.
Don't forget that the Broadway production of The Lion King is on a indefinate run in Toronto. Your DS would love it. My DD8 has seen it 4 times! The ROM (Royal Ontario Museum) is also fun for kids. Also, if he is a Baseball Fan - you should check out the Skydome where the Blue Jays play.
Sorry for the long post - we moved to Atlanta from suburbs of Toronto a year ago - I guess I'm a bit homesick! Let me know if I can help further.
