Wendy:
Coming from Michigan, I'm sure you have already hit the tourist areas (CN Tower, Niagara Falls) over the years but there are other lesser known but interesting local spots in the south of the province... the Heritage Warplane Museum and Dundurn Castle (Victorian mansion) with its small military museum (a section dedicated to the War of 1812 especially the two warships found in Hamilton Bay) are located in Hamilton. I think all the National spots are closed until the late spring (Brock, Forts George, York and Henry) but don't forget Fort Niagara just inside NY. Niagara-on-the-Lake with all its wineries is one of my favourite areas.
As for eats, in Toronto I would visit the Distillery District downtown or Greektown along Danforth Ave.
In south western Ontario, you could check out the Elora Gorge area (good easy hikes) or St. Jacobs with its antique markets. These two spots are more on the route home if your heading through Sarnia
See you in Wilmington.
Paul