Please give users the ability to replace any typewriter apostrophes ['] with typesetter’s apostrophes, [’]. These occur in contractions (I'll → I’ll, can't → can’t, etc), and genitive case nouns, e.g. Paul's → Paul’s.
This is similar to the existing rule “Consider using a typographic opening quote here.” In fact, for the sake of consistency, if you use typographic quotes, you should be using typographic apostrophes.
(Don’t do this for when ' should be a prime symbol, though).