I haven't yet seen the final ep. of the original J!, but I have seen the '78 version's finale, and Art Fleming was pretty staid about the whole thing. Of course, that version only lasted 5 months vs. 12 years, but I would think his first send-off would be similar--classy, to the point, and grateful to both the viewers and the show staff.
Alex Trebek, on the other hand, seemed to actually ENJOY his final shows. Of course, we all know about the infamous HR finale, but his final ep. of Battlestars was rather amusing as well. At the top of the show he remarked, "Welcome to the new...and soon to be the old Battlestars!" The show was also rather funny in and of itself, with both Charles Nelson Reilly and Betty White involved in a game-deciding capture with a long string of incorrect guesses by the contestants (very much like the "YOU FOOL!" incident that happened on HS 15 years later). At the end of the show he noted that they didn't get a chance to talk to Stuart Damon... "but since this is our last show, we never will! Goodbye everybody!"
I actually think this a good way to go out...hey, you're off the air anyway, why not ham it up just for the heck of it? For anyone who has seen them...were Alex's goodbyes on his other shows (TTTT, Double Dare) in a similar, humorous vein?
--Sam