I'll give some input, since Montreal has been my away from home terminal for most of my career. Dorval is neat, since it overlooks both the CPR, and CNR lines. Another good point is that there is a good hobby shop about a mile away. The down side is that things are set up mostly for the traveler. By this, my opinion is that nicer places to eat are not as handy. There are bus routes, and you could ride AMT elsewhere, specifically downtown.
If I was going to go, my advice would be to stay a bit closer to downtown. My taste is not to do trains 24/7. Nothing says that your need to spend $$$$$$ to stay at The Bonaventure, or QE. There are more moderately priced places there too. Of course this has drawbacks too. Mainly driving and parking are a pain. Even if you plan to leave your car in the hotel's parking facility, it will cost.
This is why my recommendation is to go just outside of the downtown area. Both major railroads board their crews in a hotel on Boulevard Decarie. This hotel is about a 4 star establishment. There are many advantages. First, it is easily accessed from all the major highways. Secondly, there are both fast food, and nice sit down places nearby. If your do some exploring of the local neighborhoods, you can find some mice ethnic restaurants. The prices are more reasonable than the ones which target tourists and business travelers. Another plus is that the airport is still near, and you can travel the city easily. there are metro stops within a block or so, along with bus routes.
