Chopin Etude: Op. 10 No. 4 is my default etude for auditions, exams, competitions ... etc. It's really impressive sounding, and shows off really well in auditions. It is also less subjective than some of the other etudes (most people play it the same way, more or less).
One of my friends played Op. 10 No. 8 for her audition at Indianna University, and got a scholarship for it, so it might be worth considering as well. Op. 25 No 12 is like Op. 10 no 4, except it is often considered as an "easier" etude when it definitely is not.
As for classical sonata, the opening two bar largo section of the Tempest is deadly ... the panel will usually form their opinion on your performance based on the way you play that opening largo section. The same can be said about the Pathetique. Go with what your teacher thinks will sound best on you. Or better yet, play what makes you feel more confident.
Romantic work -- I think the Ballade shows will show off your maturity more than the scherzo. THe opening motive of the 2nd scherzo is also very hard to gauge on a new piano and hall, as the silence between each motive is dependent a lot on the hall. An impressive and insightful opening passage of the first ballade will really stand out as the ballades are considered among Chopin's greatest works.
A professor once told me this about audition panels ... many profs have a hard time sitting on audition panels, as they are like cattle-call auditions, where they listen to hours of music without break. Often, outstanding performances may be underappreciated as the panel may be so tired of listening that they may confuse aspects of one performance with another. The point is, that you should make sure that you enjoy playing the program that you go into the audition and give a performance that you are proud of. And leave all of the evaluation stuff to the panel.
Best of luck.