I'm just back from a 10 day stay at the Sheraton Centre Toronto.
As a Gold member I was "upgraded" to the Starrwood preferred guest floor (24th floor) which was no different to the other rooms that colleagues were in on other floors.
Saying that, I wasn't really expecting a "real" upgrade so I was not dissapointed.
The room itself was fine although the TV looked a little old fashioned. Seeing some of the lower floors I suspected that the hotel could do with some renovation in some places.
It is possible to eat quite cheaply on site if you are not looking for haute cuisine.
As for location, you are a few minutes walk from the Eaton Centre, the metro, city hall etc - you couldn't be more central. The airport bus takes you directly to and from the hotel.
Enjoy your stay.
Stephen