Reading an article in the 10/27/09 NY Times about your declining ratings, I wondered why my wife and I used to watch you nightly without fail, but now watch you never. (We've been driven over to the Lehrer News Hour, soporific though it can sometimes be.)
I've come up with several reasons, most of them doubtless no news to you; but if even one offers a fresh idea, I'm pleased to donate it. In no particular order then, I think your numbers fell because:
The news itself grew less exciting. The elections ended, Iraq started winding down, Afghanistan produced nothing but same old same old, and the financial crisis continued to be essentially incomprehensible, despite heroic efforts to explain it with very large screen projections. In short, the mega-stories dried up.
Tabloid headlines filled the gap. Michael Jackson and the girl kidnapped and held 14 years etc. etc. were undeniably news of a sort; but to milk them day after day -- and sometimes week after week -- quickly irritated people who's IQ numbers are higher than their ages.
Talking head pundits grew more and more polarized. For every David Gergen, who actually functions as a news analyst, there was a pro wrestling ring full of costumed party liners, delivering the spin -- ranging from left to right, to be sure, but nonetheless whirling like flywheels.
Computer enhancements grew more and more manic until the screen boiled with meaningless color and motion and audio transitions whooped as if synthesizers had just been invented. Circuses are equally loud, frenetic, and gaudy, but I can't take their hoopla five nights a week.
Together, these changes produced one fatal result: your broadcast lost its essential identity as a news program.
Adding wingnuts like Fox or seizure-inducing graphics like E! will only destroy the remnant of integrity that Anderson Cooper 360 retains. Instead, why not restore the format of a true information hour? Present a wide variety of news. Keep those studio Steadicams moving but spare us fake backgrounds full of clocks and monitors. Above all, dispense with pundits who sound like spokespeople for political lobbies. Give us variety in viewpoint and opinion, but see that it's thoughtful and nuanced. (For instance, though I'm a Progressive, I listen to David Brooks with respect.)
Will this prescription return you to the top of the cable news tree? I don't know; but as the old lady said about giving chicken soup to the man who'd just died of a heart attack, "It couldn't hurt!"