Hmmm, interesting choices.
I'm not sure if anyone's mentioned T3 yet. The audio (especially during the crane chase sequence) is pretty damn good.
Of course Episode II should be a top contender for both categories. I don't even like the movie that much, but I find myself watching it just to take in the sound and visuals. That's the sign of a good reference dvd.
Oh, the SEVEN and Fight Club platinum series discs are also excellent examples of great audio and visual quality.