Could Randy Newman do an interesting version of Partytown with some boogie-woogie piano to replace one of the guitar parts?
Despite Alice Cooper's rock background, he's got a fairly normal straight ahead voice. I'm sure he'd have no trouble singing all sorts of songs. I lost track of what Alice was doing some time ago, but I'm playing "Ghouls Gone Wild" from a recent Cooper album, and this suggests that Alice could do one of the straight ahead rock-n-roll songs that Glenn does quite often. Better in the USA for Alice? Though, imagine if Brian Wilson could do that with the backing vocalists from his current band to really Beach-Boy it up.
Stevie Wonder was mentioned before, could he go back to the 70s funk era style to do "Living in Darkness"?
(Spot the person who is frantically spotifying to cover up lack of knowledge )