I had a lovely stay at the Cosmopolitan Toronto; check in was seamless, and I was offered a free upgrade! Always a pleasant welcome....
I felt like I was in my home away from home - the room was really comfortable, luxurious, and spacious. I enjoyed the xen-like touches throughout. I stayed here for work, so I was pleased the amenities in the room allowed me to work efficiently. Room service was quick and tasty. Concierge seamlessly arranged my airport transportation.
You're walkable to some sites, but still will need to utilize some kind of public transportation to get to most.
I do think Toronto has a number of really great hotel options; this should be considered if you're more interested in a boutique hotel versus a chain.More