My rule on contractions: though permissible in informal writing such as blogging, they ought to be avoided or used sparingly in formal writing. I came across the following sentence in a well-written piece in a serious publication.
"Heroic" would have pleased Ranke, who'd died nine years earlier.
The contraction distracted me, so much so that I am now writing about it. And note that in the very same sentence we find the uncontracted "would have." This is better:
"Heroic" would have pleased Ranke, who had died nine years earlier.