ARG! I've tried writing this 3 times and keep losing it!!!
OK, I'll be concise this time so I can hit submit before I get distracted...
I watch both Fox and CNN regularly. The difference that I see is that Fox puts their slant out in the open with comments and commentary; whereas CNN puts their slant within the reporting. Which do I think is more fair? Fox - because they don't report opinion as news. It's pretty clear just what is opinion.
Fox also chooses to include commentators as a major part of their network, and the commentators are almost always representing both sides of any given issue. It's a conscious choice to differentiate them from the other networks. In politics, they have one from the left and one from the right. In legal cases, they will have one with experience for the prosecution, one with defense experience.
IMO comparing Larry King, Chris Matthews and Bill O'Reilly is like comparing apples, oranges and pears. Larry King interviews famous people, mainly an entertainment show. Sometimes the interviews have something to do with a hard news story, mostly not. Bill O'Reilly makes no bones about being a commentator, not a reporter. ALL of his show is opinion! So Chris Matthews (I haven't actually seen his show...) is the only one who purports to be a hard news show.
Bumpy makes a good point. It is all about the money, and don't think that network news isn't exactly the same. No viewers, no advertising, no show. Advertisment is the "price" of a free press, and unless you subsidize the cost of reporting the news (which raises a slew of worse problems!!), the networks will always report to their selected audience.