I had in mind the Don Valley Brickworks and the Cedarvale Ravine. I occasionally used the former for my summer commute since it was so conveniently on the way, and I live near the former and take an occasional walkie/bikey there. There are probably others, including the ones you mentioned. In general, I find there are ridiculously few leash-free areas in this huge city, and most of them are located in pretty ridiculous places (and no, I don't even have a dog). But this is a bit off-topic, yeah...