Public transit is excellent, particularly if you are located near a subway line.

Plenty of waterfront access near downtown Toronto. I was there a few months ago and I shot the city skyline from Polson Pier and Humber Bay. There are a ton of really interesting neighbourhoods to explore. I'm sure a Toronto local would have more suggestions for you.

If I had time I would have spent more time shooting in Hamilton where I was staying with a friend. You can easily take the GO train from Toronto. It is a fascinating place for photography. In a really dense area you have natural areas, industrial, 300 year old buildings, modern stuff, military stuff, railroads, waterfalls...