On Chicago Hope, Dennis casually reveals that he is gay during a conversation with Aaron. It’s never mentioned again, but feels perfectly in keeping with the character and the show, and does add a level of depth.
And I can’t let this thread go by without saying that I loved the ending of St. Elsewhere, and felt that far from being tacked on, it explained a lot about the things that happened during the show, and worked very well in spite of the fact that it almost certainly was not planned from the beginning.