[Jaysun]

I'd like to be the executioner for some of the more despicable criminals sentenced to death. I'd like to whisper in his ear as I'm strapping him down, "I'm not giving you the first drug, the one that knocks you out. I'm going straight to the one that makes your muscles unable to function. So you'll still be conscience while unable to breath, move, yell. It'll take several minutes for you to suffocate. Enjoy."

Even then I wouldn't consider lethal injection a "cruel and unusual" way for these people to die.

[null and void]

I'm leaning towards anoxia. A lung full or two of pure nitrogen, and lights out. No toxic chemicals, no unseemly blood. Just a dead body.