Living in Toronto for over a decade I did not manage to visit the Bluffs park until about a year or so ago, and I was completely in shock. Its AWESOME. The bluffs are beautiful there is a large sand beach and decent washroom facilities. Several volleyball nets and a large number of places to set up camp. This is a popular park so any long weekend be prepared to see and (smell!) a large number of families with food grilling on hibachis.
You can hike up to the top of the Bluffs as well. There is parking but it is often full on weekends. You can bike, but there is a MASSIVE hill to contend with.
Absolutely gorgeous and completely unique place to visit in TO.