As any big, cosmopolitan city, Toronto has a myriad of lodging options for every taste and budget.
The grand majority of hotels in the downtown core are just a short subway ride away. However, we want to bring to your attention – as a reference – some hotels within walking distance of the colloquium site:

The Hazelton Hotel (5 stars)
Windsor Arms Hotel (5 stars)
Park Hyatt (4 1/2 stars)
InterContinental Toronto Yorkville (4 stars)
Holiday Inn Bloor Yorkville (3 stars)