The 5th on The Old Course is often a fairly easy hole, as long as you stay away from the Seven Sisters on the right of the fairway. [Stay away from them, Anthony!]
The 14th is one of the most difficult par-5 holes in golf. When I caddied there, I saw a number of 9's and 10's from visitors paying their green fees. OB right, deep fairway bunkers left, Hell ahead, difficult fallaway green with a steep false front. Not even MacKenzie's illustration of it in GOLF ARCHITECTURE does it justice.