With an over night lay over on Montreal one has three options:
1. Sleep in the airport
2. Rent a car and pull an all nighter
3. Get an airport hotel with shuttle service.
I chose the thrid option and actually reserved my room off of Hotwire for less than $50 (not bad). The Days Inn had an airport shuttle which was my only requirement. When I checked in the staff was friendly, the room was clean, all the plumbing worked as it should. Oh yes, and free internet usage in the lobby (score when you forget to do your online payments before you leave town).
I would stay again if I for some reason found myself on an overnight layover.