Saw an article many years back where they "scientifically tested" various sunglasses for use by pilots.
They recommended the 'Carrera ultrasight' lens. I have had a couple of pairs since, one with brown tinted lens, the other green/grey. Both were excellent although I prefer the green/grey.
They come with a lightweight but strong plastic frame that you can wear all day and not become annoying. I have never seen a scratch on either lens, and others that try them comment how good they are.
You can also get certain models that have slim arms so they fit nicely under your headsets, as well as being able to bend them to fit.
My next pair will definately be Carreras for flying. Oakleys are pretty good for out and about.