I just watched a kind of politicians' wrap-up on the Tonight Show, all the pols that Jay has had on in his seventeen years. And... no Bill Clinton. That's odd. Was that before presidential candidates were really hitting the talk shows? Perhaps Clinton and his sax on Arsenio were really the first of that wave.
I also wonder if Clinton for some reason didn't like Leno, maybe some of his jokes, etc., because I know he's been on Letterman since his presidency. It would have to be very specific, though, because Letterman also did so many Clinton jokes that he ran a 'Clinton Classic' every day in the days leading up to the end of his presidency.