Opening scenes of Star Trek are an awesome system test for LFE, top end and surround effects steering all in one go, so +1 for that.
Dark Knight is fairly good for a sound test, but is my preferred test disc for image quality.
Have to say I was a little dissappointed with the Saving Private Ryan soundtrack on blu-ray. It used to be 'the' reference soundtrack on DVD, but doesn't seem to have transferred over very well.