As far as requests go, I'd love to see a list of arias that you never want to hear in an audition again (overdone, too long, whatever), and a list of arias that are deal makers or breakers (i.e., if you can sing the pants off of Ach, ich fuhls, you've got the job.) Obviously, this would be subjective, but informative, nonetheless.
This is a tough question, because truly, the audition is not about me. So, for instance, I don't love Nun eilt herbei from Merry Wives, but if that's what you sing best, you should sing it!! I will still listen in the same way, and I've certainly hired people, or awarded prize money after hearing it - I hope that makes sense.
What I do think is important is to say that if you put certain arias on your list, there's a good chance we're going to ask for it - so make sure you can sing it!
Soprano - Queen of the Night, (at least a portion of) Zerbinetta
mezzo - Non piu mesta, Komponist
tenor - Tonio - Daughter of the Regiment, Boheme, Faust
baritone - Largo, Il Balen, Credo
bass-baritone - Blitch, Basilio
bass - a pretty wide open field, but certainly Filippo, Osmin
This is my own list, but you see where I'm going with this - if you have these on your list, make sure that you not only can get through them, but that you can shine. This is a case of no points for effort. Keep in mind that people who audition you want to know that you make good choices too - that's part of the audition.
For instance, if you're working on Cenerentola, but you're not quite ready to sing it, sing your Dorabella instead - I won't judge on what you DON'T sing, only what you DO sing.
But, whatever else you worry about, don't worry about whether I like the aria, or I'm tired of it, etc.