That's why they use AC for the electric chair. From what I've read, DC is more likely to just burn you but AC can kill you. I was once hit with over 500 volts AC that went in my left arm, crossed my chest, and exited my right hand. Man, that hurt! Luckily, the current was low enough that it didn't kill me.

AC is used for long distance transmission because it's much more efficient for high loads than DC. You can send a million watts over an AC line at 250,000 volts and only need 4 amps to do the job. The higher the amerage, the greater the electrical losses on the line due to the implications of Ohm's law (or the AC version). You then use transformers (which don't work with DC) to step down the voltage at the user end.