I’ve always liked “True” by Spandau Ballet, or “Honesty” by Billy Joel. As long as it’s in my key, I think I can do a pretty good job with either.
I sang a solo from “They Call the Wind Maria” before a live audience last year during a choral performance, and that was a lot of fun. But probably not the right type of song for American Idol. 
I’d sing something I wrote. Maybe Mercy or Ask the Wind.
That’d be fun, if they insisted on a cover then,
"It’s Not My Cross to Bear" By the Allman Brothers or a banjo version of the Grateful Dead’s Ship of Fools.
As long as nobody points a laser at my crotch.
“No, Mr. petcat – I expect you to die!”
First I’d see if I could get away with doing “Closer” by Nine Inch Nails. If they balk at that, I’d try to do “Beyond the Sea” by Bobby Darin. That’s usually the first song I start singing whenever I get embarrassingly drunk.
“Kiss Off” – Violent Femmes.
Or maybe… “Lullaby” – Stephen Lynch
“Swing Low, Sweet Chariot” I could show off my range (Barry White to Barry Gibbs).
“SuperfreaK”…yow.
Something by Jeff Buckley I would imagine… .like Grace or Hallelujah…
Hmmm looking at that you would not think that I wasn’t a Christian 
But I’m not… I just like Buckley… Maybe I would sing Mojo Pin… that is good too…
I’d go for “Mmm mmm mmm mmm” by the Crash Test Dummies. Even if I stunk up the joint, I’d still have fun doing it.
Steamroller Blues by James Taylor.
Wish You Were Here - The Pink Floyd
Time In A Bottle - Jim Croce
“Too Drunk To Fuck” – Dead Kennedys
Hepcat–you stole my song!
Heh heh…I’d do “Time in a Bottle” by Jim Croce or…(just to show off my range)the funky soul version of “Zip A Dee Doo Dah” from my 'Music from the Parks" Disney CD.
IDBB
“Muhnuhmuhnuh,” made famous by the Muppets back in the seventies.
Or, just to show some disdain for the entire concept of the show, “The Entertainer,” by Billy Joel.
“The Show Must Go On” by Queen
Mr. Rilch and I were talking about this while watching the auditions. If either of us did audition, he would do “The Way You Look Tonight” by Tony Bennet (?) and I would do O mio babbino caro, by Puccini. Both would probably get us eliminated whether we could bring them off or not, since neither is a pop song, but I’d like to see Simon’s reaction to opera.
In the finals, either “Total Eclipse of the Heart” or “Building a Mystery”. In the latter case, I hope I would remember to change “beautiful f—ed up man” to “beautiful brown-eyed man”.
I would be singing Counting Crows “Mr. Jones”(see sig), it would be incredible fitting if I won by playing that song. It’s about wanting to achieve fame and greatness.
Danzig’s Mother.
I’d even wear the mesh shirt and welding gloves.