> should one be allowed to request a death penalty?
If prison conditions are bad enough for someone to even consider that, that's a damning indictment of the prison system.
> Wouldn't 150 years in jail be considered cruel and unusual punishment?
Certainly not unusual, and jail doesn't seem inherently cruel, if we believe some people are enough of a danger to society that they need to be kept out of it. (Of course some particular jails might be cruel).
(I'm using the British English meaning of "jail"; I'm aware that in US English the term has a technical meaning)