I used to live on Ste Catherine St. Hotel du Maritime was on Guy and Rene Levesque, was a block walk to Ste Catherine and was relatively inexpensive to stay in. It also had a very nice indoor pool and was very clean (this was about 8 years ago though)
I've heard good things about the Delta on President Kennedy. My Mom used to stay in the Holiday Inn on Sherbrooke, just past McGill, when she was on business.