This is indeed a factor. I still haven't made up my minds yet.
How about the JW Marriott -- I understand that this is not a Marriott forum and you may not have extensive experience with the JW property.
For what you want, the Westin sounds ideal. First, as you will have club access you will have some extra space not to mention snacks and soft drinks and breakfast. I can't imagine the st Regis and ritz will be as kid friendly for parents traveling with a one year old. Also , the walk from the Westin to the mall is much easier than the ritz. As for the Marriott which is the old Sheraton across the street, I stayed there for years and it is a very poorly laid out property. The Westin is definitely better.