I don't know... I think it has to do with demeanor and style more than physical appearance. Meryl is more suited for Desiree than Close, and it has nothing to do with their actual ages... it has to do with how they come off to an audience. Close comes off more older and severe (to me), and Meryl has more "youthful charm" to her still.
Still my first choice (as I said before) is Annette Bening.
Remember, though... Angela Lansbury was playing everyone's mother before the age of 30. In some cases, her children were the same age as she was or only a couple of years older (as with the Manchurian Candidate). It's all about perception... although at a certain point you can't lick "Father Time." And I think it's easier for actresses (in particular) to play older than it is to play younger than their age. God bless Bette Davis! She tried to play younger several times and it was a total train wreck.
...And I hope you know my "third smile" comment was a joke! Glenn is a fine actress... I was just going for the laugh. Glad some of you got it!
"Jaws is the Citizen Kane of movies."
blocked: logan2, Diamonds3, Hamilton22