I see the OP is HHonors Gold. If you want to stay true to Hilton, we have a Hilton Garden Inn in the downtown area:
http://hiltongardeninn.hilton.com/en...DTGI&WT.srch=1
And of course, there's the main Hilton downtown:
http://www1.hilton.com/en_US/hi/hote...1&pSearch=true
Both of these Hilton properties are fine. The Garden Inn is a small property that's just a block away from the cool, hip area of Queen Street. The Hilton is a large tower with a big ballroom complex for meetings / conventions etc. The Hilton is located on University Avenue which is a main thoroughfare in YYZ. It's also just a block away from the Eaton Centre which is the main shopping mall downtown.
As mentioned previously, Yorkville is the high-end section of town so if you can find a nice hotel here, I'd recommend staying in Yorkville.