When I was intensely searching for a new game to join, I was desperate enough to check the lists of wanted characters from various games. Out of all the characters, I was intrigued by [Mother] Bennett. The only reason I didn't apply was because it seems a bit daunting to join a game with history and interactions that have already happened between current characters (or rather, her chilren). I'd feel like I'd be playing catch-up for a while and not be up to par with role playing such a character. I do, however, think I'd be awesome at playing someone who is cold, neglectful, and verbally abusive.
Obviously, I'd have to do some researching in-game and talk to the muns who play her children, but I am still interested if it's available. As far as PBs, I was thinking either Finola Hughes or Eve Best. If you'd like to chat about it more, I'm available on AIM (haiberu13), or I can e-mail you at the address mentioned above.