For nearly 30 years, Phil Donahue conducted a daily talk show, first out of Dayton, Ohio, before moving to Chicago, where the show went national in 1970 (the series launched as a regional entity in 1967). Rather than sit behind a desk, Donahue walked around amidst the audience, microphone in hand, the precursor of later daytime gabbers such as Oprah Winfrey and Sally Jesse Raphael. He dealt with important social issues, pop culture (celebrity guests have included David Letterman and Vince McMahon), and controversy, such as steroids in wrestling (McMahon appeared on this show and got into it with wrestling journalist Dave Meltzer).
However, all good things must end, and so Donahue decided to hang up his microphone in 1996 to spend more time with his 2nd wife, actress Marlo Thomas. I don't think he'd be too thrilled with the way his show's format gave way to the lowest-common-denominator-coveting tabloid trash we have today. Multimedia, which distributed Donahue and Sally Jesse Raphael, ultimately was absorbed by NBC Universal.
Here's a show from the 90's, focusing on game show icons Monty Hall (Let's Make a Deal), who must've thought he was too cool for the room and appeared via satellite hookup, Tom Kennedy, Peter Marshall, Gene Rayburn (who had looked a little bigger by this point), and Wink Martindale. Wink uploaded this episode on his YouTube channel.
Part of the reason there's a glut of talk shows now is that you have the tabloid trash (Maury Povich, Jerry Springer) shows that won't go away, while Ellen DeGeneres keeps the variety format alive, the way Mike Douglas, Dinah Shore, & Merv Griffin did it before her. Phil, admittedly, would be more proud of those shows.