Hi Adam - This was a topic on this board some time ago and, by what I can recall of what was said then, the Carter descendants appear to be staying on top.
I know that the Straus and Astor descendants are still prominent in New York and, since the Guggenheims were such a large family, I'm sure plenty of them are still around.
I know nothing about the Wideners, but I know that the FitzEugene Dixons (the family George and Eleanor's daughter married into) are still in the Social Register. I don't know about the Thayers either.
The Duff Gordon and Rothes families maintain their titles today, though this says nothing about their financial status.
It seems that the Brown money is long gone. The Baxters,
Major Peuchen and Mrs. Harris also lost their fortunes, and
Colonel Gracie's widow went broke after he died. There was talk of Dr. Dodge having financial woes at the time of his suicide, but I don't know if that's true. In any event, his wife might have had her own money, and I think young Washington did alright for himself. Julia Cavendish also sustained heavy losses later in life, according to what was once said on this board, but I don't think she became positively poor.
My mother grew up with relatives of Georgette Madill, and that family is still sitting pretty.
This is all that comes to mind right now. Talking about money is vulgar, I know - but fun!
-Brian A.