As beautiful as the Niagara Falls may be, the price of beauty is $20. I wouldn’t risk parking at the $12 lots just up the slope though because whenever you have to walk down to see the falls you’ll always have to hike back up to get your car. At Niagara Falls, the hikes are steeper than the official parking lot prices.
Personally, I wouldn’t recommend going to the US side to see the falls. Although the nice part of the falls are over on the other side, it’s best views belong to Canada. The Simpson’s depiction of the falls aren’t quite accurate; while there are shady motels and seedy casinos on the US side, the Canadian side looks to have taller and larger casinos. I wouldn’t know what they were like, I’m almost sure I’ll have less luck than at the Canidrome.
A walk along the paved pathway beside the falls will take about 20-30 minutes including time to snap a few pictures. I went on a weekend during the summer and it wasn’t as crowded as I imagined it to be. The food choices are more expensive, but no more expensive than airport food. To make up for it, drivers may consider filling up in the US before returning to Toronto.