That's what I was thinking in a way, that her version of Leslie would've been tough in more of a "confrontational" way instead of Lee Grant's more low-key way.
Another one might be Kay Freestone. I'm not sure about the entire role, but when Kay starts thinking about her poor upbringing, or having those "tough love" moments with Valerie, you can imagine Eileen Brennan playing the part.
Grant, I was literally going to reply and mention her as Kay Freestone. Clearly, based on my "Mark MacAndrews" handle, I have some fondness for this episode. I could see her easily sliding into that role.