Here's part one of an entire episode of David Letterman's original NBC talk show. Not "Late Night" - this is the show that aired in the morning.That's right - NBC thought Letterman's schtick was perfect for the game show and soap opera crowd, and cleared 90 minutes from it's schedule (including the long-running Hollywood Squares) to prove it.
The show was a flop. Within weeks, NBC shortened it to an hour, and after four months - it was canceled.
I only ever remember seeing the 90 minute versions when they first aired, and although there were a few memorable moments - I recall the show as being mostly boring. From what I also can remember, critics mostly praised the later episodes, and the show went on to win a Daytime Emmy.