Senator Al Franken (D-MN) made a rare appearance on national TV, sitting in with his old friend David Letterman. And while they were discussing the ongoing controversies in Letterman home state of Indiana, the former comedian Franken had a suggestion: Dave should go back to Indiana — and seek to join Al by running for the Senate, too.

Seth Meyers took on the endless media speculation and questions to Senator Elizabeth Warren (D-MA) about whether she’ll run for president — and her repeated responses that she is simply not doing so.

Conan O’Brien sat with the one and only Ringo Starr, who talked about how he had grown up with the most hardscrabble background among the Beatles.

And James Corden hosted Katie Couric, who talked about the ongoing controversies with her former news colleague Brian Williams, and called for a sense of mercy and consideration in the popular culture.