Marie Curtis.
Not an obvious selection as it is not in the heart of the city, nor a particularly nice spot for that matter (need to be a confident upwind rider, okay with gusty conditions, and comfortable with a slightly awkward launch and land), BUT, the "mississauga side" of the park is not conducive to a lot of beach goers and there is a big grassy park under a wind shadow that makes for an ideal lz.
More importantly for you, it is only a short walk from the Long Branch Go Train station.
http://localkitespots.com/kitesurfing/Ontario?site=1205182260321&static=1
Until the bad weather clears out Ash Bridges (i.e. fall), this is a fine destination for anything with a healthy amount of Easterly wind.