If there was an award for "most picnic tables", Boyd Conservation Area is definitely in the running, if not the winner.
This park has lots of green space along the Humber River, which is partially treed and partially grass. It's only open on the weekends so time your visit carefully, but the peacefulness is worth the wait.
In addition to the hundreds of picnic tables, there are also 17 bookable picnic spaces, picnic shelters, water and outhouses in the park.