I have a theory
She seems to suceed in roles where she has "man trouble":
Young Frankenstein: the other woman(even if they didn't elaborate on this), as well as dealing with a driven man.
The Conversation: never saw it, but she says that Gene Hackman and her have a less than truly intimate relationship.
Close Encounters of the Third Kind: BEST EXAMPLE! Grows ailenated (intentional pun) from Richard Dreyfuss as he grows obsessed with ailens (but really, it was just a matter of time...that line, "Remember when we used to come up here and look at ourselves?" and the fight scene are almost painful to watch).
Oh, God: never saw all the way through, but she was doubting John Denver for a while there.
One from the Heart: She and F. Forest are on the outs
Tootsie: OTHER BEST EXAMPLE! Dustin Hoffman downright tortures her, playing with her feelings and what not.
Mr. Mom: She and Michael Keaton struggle with the gender roles (not in reality...both gave flawless performances)
After Hours: She seemed to be a nice girl, and Griffin Dunne blows her off.
Heck, even in Dumb and Dumber: she's the trophy wife (according to the novelization).
I also agree with a previous post: total MILF in a lot of those movies, and even lovely now.
"The sexiest part of a woman is above the waist-- the brain. But the pussy is a close second."
Tracey Ullman (as Madame Nadja)