It depends on when you are going to Montreal in July. There are all kinds of activities in July ranging from Jazz Festival to Comic Con to Just for Laughs... The downtown core is not big but some are closer to some activities than others...

For bachelor party stuff, I would guess closer to Old Montreal would be more fun - thus the W and Westin. I think the Quebecker have an interesting "parade" tradition for bachelor / bachelorette parties doing crazy things in public...

I am not sure who has lounge and who has not. The Chateau Champlain is the M Lounge on the first floor so it is not that great.