The most important thing is to be absolutely clear in your Living Will and Final Will. When my grandpa was dying of cancer, the family -- us -- had to decide whether or not to take him off life support. In his Living Will he stated that he wanted life support to be removed something to the idea of "when life wasn't comfortable or there was little hope of recovery." Those aren't the exact words; they escape me, but you know what I mean. So it caused a big ruckus between our family of what we should do and what he would've wanted (he was unconscious) because there was so much gray area in his wishes. No one knew what we should do and what he would've wanted.
It happened too with his estate. People fighting over stuff and getting all mixed up.
A good idea is to go over your Living and Final wills with a fine-toothed comb in the presence of a lawyer. Also tell family or friends your exact wishes. More than one with the same story.
The idea is to eliminate as much "maybe" as possible so everything goes smoothly.
Just my two cents.