As all these great comments come in, and as I pull together my Bibliography (until 5:30 this ayem, thankyaverramuch, and still not done), it's kinda shaping up in my head that what my thesis really almost has to be is: Superman vs. Spider-Man.
While the Daily Planet crew were gaily disregarding ethics and often the law in their quest for "scoops," they were treated as heroes, and the readers were expected to think of them that way. By contrast, J. Jonah Jameson is the first prominent journalist in the comics I can think of who was an out-and-out jerk -- not quite a villain, but certainly no hero. And, while the Planet staff had no problem acting as Superman's PR firm (although they should have), it was Peter Parker who first realized that he was acting unethically (at least when he pretended to be Electro), and therefore first asked the reader to consider that maybe not all reporters were all that cool. With advent of JJJ and the Daily Bugle, journalism in the comics kinda grew up, where reporters could be jerks as well as heroes, fuzzy gray instead of black and white. An argument could be made -- and I will certainly make it -- that the door was kicked open for characters like Jack Ryder later in the decade. (Sure wish I had more than one example. I guess I could stretch with Vic Sage -- and I can draw a line to unpleasant Planet people like Morgan Edge, Cat Grant and Steve Lombard.) That's the direction my brain is heading at the moment. Not necessarily a decade, but a sea change in the use of journalism as a story device. Spider-Man's Daily Bugle vs. Superman's Daily Planet.
Yes, both Ryder and I believe Vic Sage were Glenn Beck and Rush Limbaugh types before they existed IRL. One of them had a show at some point called You Are Wrong! I need to get an example of that, because it illustrates some of my points.
You know, finding instances of JJJ being unethical are pretty easy (funding Spider-Slayers, front-page editorials, fixing the news to make Spidey look bad, creating the Scorpion, hiring Kraven and Ka-Zar, etc.). Finding instances of JJJ being ethical seems to be my challenge now. I know Marvel has played JJJ both ways, and that "gray area" is part of the concept that I need to illustrate. Anybody remember a time when JJJ was on the RIGHT side of an ethical issue?
I've never been clear on whether the Bugle is a real newspaper or a tabloid, either. Again, Marvel seems to play it both ways. I intend to ask Roy Thomas and Danny Fingeroth that very question, instead of speculating. Then I can find examples to back up (or refute) whatever they say.
You mentioned Cat Grant, Cap, so I have to ask -- did she exist in the era you're examining? I had the impression she was introduced in the Byrne years...