Agree with redtsorm- Generally plats will get upgraded to a fantastic suite- which is nice (ask for a corner suite if available), but not absolutely amazing. I stay at this property usually once a week and thats my standard upgrade- however they have hooked me up in the past due to my loyalty (ex. I had a Wow suite upgrade this past Valentines day weekend).
If it is really special occasion I'd recommend trying to get a Wow Suite (bi-level loft like suite with huge windows)- even if you have to pay extra or use points. Email the GM and see what they can do- the management at the hotel is very responsive. I know they routinely sell out, especially on weekends, so don't show up the day of check-in hoping to score one. They aren't "select standard suites" so they don't have to upgrade platinums even if they are available.
As for your first time at a W- I think you will be impressed if you are looking for a scene. The check-in will usually have loud music playing and everyone working there is good looking. The only real annoying thing is that the lighting is very poor. There is generally no overhead lighting in the rooms- just desk lamps or side table lamps. Ipod docks/speakers are standard and all of the showers are waterfall- with a large head pouring water down vertically from the ceiling. Bliss products are great- body butter, foaming fash wash and lemon/ sage soaps/shampoos. Hallways are especially dark and the club in the lounge gets pretty packed at night (you can always jump the line as a hotel guest). All food/ drinks are expensive so plan to shell out cash if you want to eat on site- for ex. a bowl of raisin bran is $17 and coffee is $9. The restaurant Otto is decent, but way overpriced ($30-$40/ entree). Valet is $40 which is funny because the hotel isn't in the downtown area and theres lots of cheap street parking. Internet is also $25/day (though you get 1 hour free if you log in from the lobby and then go up to your room).
Overall its a cool hotel in a unique location- between the downtown and Old Port. Staff will bend over backwards to make your trip pleasant which is why this is my hotel of choice in Montreal. Let me know if you have any other questions.