I always get a car whenever I am in town just for convenience sake. It greatly enhances my mobility around town. I have stayed at the Hyatt over 10 times now, and I had to valet park my car each of those times. Since my car was a rental, it never really bothtered me all that much how they treated the car or whether or not they would snoop around looking for things, as I had nothing in it.
Basically, at the Hyatt and all the other hotels in mtl that require valet parking, the biggest problem that I have encountered is that I may not always get my car in a timely fashion if I am in a rush, especially during the wee hours of the early morning. Sometimes, I would have to wait like 10 minutes before I found someone to retrieve my car.
Other than that, there has never been a problem with valet parking. Heck, oftentimes, they even left the seat setting exactly the way that I had left it.
In summary, I don't think you have much to worry about when it comes to valet parking. I have done it over tens of times and never had a problem.
I guess my biggest concern when it came to valet parking was the fee one had to pay.