Hi Jon,
like Jilly, I have been to Toronto many times - its a great city. I usually stay at the Courtyard Marriott on Yonge Street. I stay in Marriott hotels a lot and the Courtyard is a brand within the Marriott chain that are slightly cheaper than the full main brand of Marriott hotels. There are quite a few hotels on or near Yonge street (not surprising since Yonge Street is the longest street in the world!!) - by the way it is pronounced 'Young'.
Anywhere on or near Yonge Street (i.e. several blocks either side) from the waterfront right up to Bloor Street is a good bet(Bloor street is in an area called Yorkville which is a few miles north of the harbour, which is where a lot of expensive shops and smart bars and restaurants are). You could look up somewhere like
http://www.expedia.com.
Enjoy. Go up the CN tower if you are not afraid of heights!
cheers
Jock