Actually, I have a pair of black old navy khakis that are awesome, flexible, comfortable and durable. That's the perfect trifecta of pants-hood.
If you want to see them, look no farther than the Beast Coast gallery. They are strapped firmly around my supple waist with the belt of justice.
Anyway, I dislike shorts mainly because I don't wear them on a regular basis, so when I put them on for Parkour, I have to completely recalibrate myself for the flopping all around, wind on my legs, etc.