interpretation...

[rhapsody7900]

Ok, I know this is a totally subjective topic (and its arguable irrelevance and lack of cohesiveness is likely to offend some), but I am curious as to which pieces are the most difficult to interpret.  I ask this because a friend of mine considered Chopin's Fantasy in F to be the more difficult than many of the technical giants due to the intricacies in its interpretation.  

I know that there are many other variables to consider in answering such a question, but I'm more interested in what you all think in the most general sense.  

... well, ok, one column for large scale works (concerti, sonatas, trios... which obviously are generally more demanding) and another (like the fantasy, solo repertoire, etc.)  

[Max]

In a general sense, it would be a piece which has either a very strict interpretion, or a piece with very little instructions.

Also any piece with a wide variety of interpretions is hard (the Chopin Etudes, for example - if you're looking to make them 'personal' you're in for a hard time).