hi franklindriessen,
I think a good audition repetoire will show your best qualities and understanding in all different kinds of music. So here are some hints, hope you find them helpful.
1) Choose pieces which are contrasting, like the requirements in historical styles, but also contrasting in their characteristics, such as tempo, articulation, range of expressions etc...
2) Arrange repetoire so you don't have 2 very technical and furiously fast skillful (and tiring pieces) together, have a serene change in between.
3) Choose a piece that you think you will like to perform and know that you will do a good job at it, sounds silly, but musicians all have different intepretations on different works, choose a piece that you think you could intepret well, which means having the composers intentions as well as some originality in personality of the piece.
4) Don't over-work yourself...hehe, the audition doesn't depend on how long pieces are, just like an essay I suppose, choose efficiently yet thoughtfully. (if that makes sense, if it doesn't, tell me.)
So you have to play 5 pieces I gather, a bach, beethoven sonata (at least one mvt), a romantic, a more contemporary, then a more contemporary one to the contemporary. I also did an audition similar to yours for university around 3 years ago. I played a bach p+f and beethoven sonata (either 3rd of appassionata or a very early work, can't remember). For romantic I played a Liszt etude, then a Debussy for a change, then prokofiev. I can't tell ya what pieces you should play, have you got any that you're particularly impressed about? Listen to more music and i'm sure you'll find pieces you'll like. Goodluck.