I don't know anything about smoking rooms. I know that most chains will have them... Holiday Inn Express maybe?
BTW I just went on Kayak and sorted Montreal hotels by price. The first few pages are NOT hotels but seedy by-the-hour brothels. I can't believe they'd even list those on travel sites.
I know you know better than to stay in a crappy old place east of Saint-Laurent, but just in case you were tempted by the sub-$50 prices.