Someone once said "Toronto is New York run by the Swiss."
It is clean, safe and probably the hippest city on the continent, next to N.Y. (but, more so than L.A.).
Newsweek magazine once rated Toronto the 3rd best place in the world to eat. (Paris and NY were 1 & 2) Every type of food imaginable is in this city.
Time magazine rated Toronto the 3rd best place in the world to see theater (NY and London were 1 & 2). They have more movies houses per capita than any city in the world, and host the most prominent film festival next to CANNES. The theater district reminds you of NY. Most of the same plays are in both cities at the same time.
They have tens of miles of underground city so you never even have to come up for air, and the city is only 1.5 hours from Niagra Falls.
Only N.Y. is bigger and has 'more' to offer than Toronto.
But, you have to love city life. If you are some hick from a small town (even in Ontario), you probably won't dig it (or understand it).
I live in Orange County, CA, south of Los Angeles. I only wish Los Angeles was as hip as Toronto. I'd spend all my time there.
I highly recommend Toronto for 4-5 days (or more).