1. The Westin Prince is not a bad property, BUT it's not downtown (not where everything is) and for going to shows, games, nice restaurants, etc. it is not the most convenient location. HSIA only in the higher floors.
2. The Westin Harbor Castle is nicely located (in the winter it's still a bit of a walk to downtown, but the Harbour Front has its own attractions, etc.). I recall they even have some sort of shuttle to some places downtown, but I may be wrong. You can actually walk to downtown theatres, etc. anyway. Rooms are pretty standard, but not bad. The revolving restaurant at the hotel does not serve the best food, though.
3. The Sheraton is a convention and tour bus hotel. I wouldn't stay there at all. But it is right downtown, across from city hall and connected by underground walkway to most places downtown.

All three properties are supposedly AAA four diamond, though I wonder why. The Harbour Castle is quite nice, esp. if in summer. But this time of year, you might want to closer to downtown attractions. I just came back from a visit to Toronto, and because of my view on these three hotels, I actually stayed at the Eaton Centre Marriott. Cheaper than the Sheraton, all rooms have HSIA, and parking is only $16 for self-park and $20 valet, as opposed to $33 at the Sheraton. (All $$$ in Cdn, about 75 cents now).

Try the Tundra (at the Hilton) and the EPIC (at the Royal York) for some really nice meals... ENJOY! TO is my favourite city.