I've spent a fair bit of time in Montreal over the years - always at downtown properties. Here is my simple list of preferred Marriott hotels, based on a formula of cost, quality and elite recognition averaged together...
1. Sheraton on Rene-Levesque Blvd.
2. Delta on President Kennedy Ave. (longest walk)
3. All other properties in downtown core (incl. Renaissance, Residence Inn, etc.)
4. Chateau Champlain.