The Perfect Songwriter For Idol Theme Show?

One post on a previous thread suggests Paul Simon, noting that there would be great songs from a less than great voice. I agree with the principle, and think PS is a good choice. I was wondering if people had other good choices, too.

In addition to limited singing ability and great songwriting ability, I would also add a few more criteria for the "ideal" idol theme:

Artistic credibility (limit cheesiness inherent in the show)
Stylistic variety (fairness to all contestant factor)
Production experience (coaching others)
Hits in the catalog (familiarity for viewers)

At the risk of prosthelitizing (sic?), I'll nominate Todd Rundrgren.

Any others?