The general consensus is that rock or pop music is too repetitive to be used well in competitions.
For demos, to attract the non-flier, you would need a hit that transcends time or something very current and huge.
I'd suggest any recent Lady GaGa song.
Bad Romance has over 261 MILLION views on Youtube. It's too long, but you can always make a shorter version or just ask the people to fade it near 3 or 4 minutes.
There are several LGG songs with over 100 MILLION hits. Just listen to a few and pick out the one that offends you the least.
For many of us, she is Lady GagME.
Here are a few to consider:
Don't Dream It's Over: Crowded House (slow)
You Ain't Seen Nothing Yet: Bachman-Turner Overdrive (moderate)
Can't Get You Out Of My Head: Kylie Minogue (pop/dance)
Pride (In the Name Of Love): U2 (slow)
Tom's Diner- DNA Version: Suzanne Vega (slow)
Ain't No Other Man: Christina Aguilera (nice variations in tempo)
Hysteria: Muse (my favorite modern rock song)
Every Morning: Sugar Ray (relaxed)
Human: The Killers (you'll have to cut 6 seconds)
Those are on my iPod between 4 minutes and 3:44 that may be appropriate. Got lots more if none of those strike your fancy.