If your kids are younger than about 10, I strongly recommend the Storybook Gardens in London Ontario. Think of a McDonald's Playland times 1000 without the bad smells, throw in a really cool rope climbing thing that Dad can enjoy too, and a splash park for a hot summer day, and you can fill most of your day at bargain basement prices.
And hey, it's only a 10 minute drive from civilization, so you don't have to pay amusement park prices for food.
http://www.storybook.london.ca/
