Back in 2005, I practically lived at the Cambridge Suites for work and I loved it. I was there off and on for months. The nicely appointed rooms are like mini apartments and have everything you need for a comfortable and productive stay.And you are walking distance from most locations downtown and not even half-a-block from the Eaton Center (which you can also reach underground through the PATH system).
I returned on business in mid-December 2011 and was pleased to discover that not much has changed...but keep in mind that the reasonable room cost does NOT include $22-a-day for parking, $10-a-day for the spotty (at best) wireless Internet connection (which only covers one device at a time), and $13-a-day for a continental breakfast (scrambled eggs, fruit, cereal, pastries and toast). You can't get around paying for the parking or very spotty Internet, but you can get a much, MUCH better breakfast deal by going to the Sunset Grill on the corner of Richmond and Yonge...mere steps away from the hotel.
Also, be careful driving into and out of the parking garage. it's very narrow fit to get in and to navigate the ramp (particularly on your way out) and the parking spots can be a tight fit, too. There's a reason why there are so many paint scrapes on the pillars.
All in all, it's a great place to stay for business or pleasure to Toronto.