Blacken said:
Are you dividing late and late-late? Craig Ferguson has some pretty great, serious interviews on a regular-ish basis. (He's totally not right for the Late Show though.)
But this is a function, in large part, of him being a second (or third) string host. People that appear on his show are typically either lower-level stars, or moderate-level stars that are either not promoting anything or are in the shoulder season of their promotional efforts. Those people can afford to be off-message and talk about semi-interesting things because there's no need to all-out PUSH THE MOVIE/SHOW/ALBUM.
JMOH is right; interviews on any of the major late night shows, by design, dull. They are usually in the following format:
1) [Person X] everyone! How are you? Welcome back.
2) So I heard you [were in the news for/like to do] [something funny/odd/endearingly embarrassing; all designed to paint the guest in a human light]?
3) So you have a new [album/movie/show] coming out. Let's talk about it.
4) [What is it like to work with actor/director/producer] / [So this was hard for you because you recently lost a relative/went to rehab/something serious to paint the guest in a human light]?
5) Let's hear it for [Person X]!
And the dynamic in place demands that the interview be that boring, because if Denzel's publicist thinks that Host A is going to divert from the script and not let Denzel talk about the new movie for at least 2 minutes, and instead focus on Denzel's crappy movie from 2 years ago to get some laughs, forget it; publicist is taking Denzel to Host B.