I have stayed here The Omni for a couple of nights with a 10 month old on my own.
They were very accommodating - nice big room. It's near the Mont Royal park and university area and main shopping area, but the immediate location quite quiet, but close to the action. An easy/pleasant walk to the riverside/old town in about 20 mins.
They gave out a children's activity pack with toys, crayons etc
The concierge was very helpful with ideas for kid-friendly restaurants / activities.
I only ate breakfast there, but it was buffet-style, they had high-chairs and a tolerant business-y clientele.
The underground city (shopping) is a bit of pain with a buggy if you still use one - bit like the Tube with lots of different levels separated by small flights of steps. Had to keep going up and down at different entry points to get round this aspect.
Very nice city though, wish I had had a bit more time to explore.