Strangely, I don't think (without knowing the details yet) that this case is one where I might be inclined to go for a death penalty. For me, it would have to be for cases where there can be absolutely no doubts whatsoever about the guilt, the intention, the state of mind, the lack of any mitigating circumstances. I am not sure it would qualify. How could we be certain their intention was to kill the people in the house, as opposed to simply wanting to burn their house down and give them a terrible scare? They probably did mean to kill the people inside, but "probably" doesn't cut it if I was to be persuaded about a death penalty.
I'd give them a full life (i.e. never to be released) sentence though.