Actually Toronto is not a good place for sightseeing, but I had bad weather as well and my friends there suggested to go there in summer cause it is way more fun then. Public Transportation (TTC) is the worst I have seen in the whole world. Also TTC employees doesn't know or don't want to tell you which train or bus to take. It took me a long time to figure out what bus to take at 4am in the morning to go to the airport. It is the 300A bus. You can find the route on the internet.
Insider Tip:Aquarium is a new museum and worth to go.