I'd wager that every one of those people is guilty. It's really difficult to be put to death in America for a crime you didn't commit. Too many appeals, and judges don't dole out the death penalty when there's anything even remotely close to a reasonable doubt.
BMWBoy, I don't know which prisons you've been in, but the ones I've seen had nothing except rows of single cells with solid steel doors, a library, a weight room, and several small (single man) "courtyards" surrounded and separated by rolls and rolls of razor-wire where the prisoners could go outside once every week or so for about an hour. The prisons I've seen didn't have cable TV and all that crap. I think the prisoners' families are allowed to bring televisions to the inmates in some prisons, but it's not provided by the state.
But then, I've only been in state prisons. I somehow doubt that the federal prisons are any better. Couty prisons aren't really too bad, but you won't be in one of those for more than a year. For longer sentences, you'll get sent to a real prison.
P.S. I'm not really for or against the death penalty. I can't decide whether it's good or not.