I definitely want to be warned about the death of a major character. I use the warning as a time-saver; when I see the warning, I don't read the fic unless it's been rec'd by people whose tastes cooincide with mine.

Since I mostly read BtVS/AtS slash, a warning of character death usually means vamp!Xander, which I don't enjoy reading. There are always exceptions, of course; the character death could refer to a peaceful death after a long and productive life -- but really, how often does that happen? :)

My reading time is so limited, especially lately, and I'd rather spend my time reading fic that doesn't leave me feeling heartbroken.