I'm with Rob -- the tune of any song can be made into an interesting instrumental piece.  You as the arranger must like the tune or you won't do it the justice it deserves. 

 

Not that I  make instrumentals out of song tunes, I just don't sing the words and play the tune at the same time...

You just have to like it.  Any can be interesting.

 

Just a poll, and I hope this question makes sense. When making instrumental arrangements of a vocal/lyrical song, like any given country, rock, or pop song, does anyone feel that certain types of songs, with certain compositional attributes, make for better instrumentals, or can literally anything make for a beautiful or interesting instrumental with the right arrangement?