I generally have the praying for everyone when I am in the temple. I just say to God "Keep everyone happy". This is selfish notion of mine since I have been taught that you lead a good life if you pray for everyone :)
But there in lies in the confusion. It is definitely not possible for God to keep everyone happy in this world. We do a good job of cheating, robbing, killing our fellow human beings.
I reckon the thing that I should be asking for is "Give everyone the strength to overcome their difficulties" isn't it?