If you are visiting Montreal, I recommend staying at the Marriott Chateau Champlain. The hotel is not only convenient to Gare Central--perfect if you are arriving/departing via Amtrak--but also to the Metro, the Underground City and many local highlights including the shopping on Rue St. Catherine. The hotel really looks just like a cheese grater from the outside.
Our hotel room was comfortable and I enjoyed the amenities in the bathroom as well as the views of the city. The staff was helpful and friendly, particularly the lifeguard at the pool who gave me recommendations on where to buy a purse when the one I brought broke and needed to be replaced. The pool and hot tub were especially nice but the pool is too warm for lap-swimming, if that's what you're looking to do. I didn't come to Montreal to train for the 2016 Olympics so I just enjoyed relaxing in the water like mermaids do.
We got an excellent deal on the hotel room (you know I love a bargain!) but regardless, the Chateau Champlain is a great option if you're looking for a place to stay in MTL.