Some possibilities
Taylor - I'd love to hear Taylor try something like Hotel California by the Eagles or Cold as Ice by Foreigner.
Elliott - 'I want you to Want me' by Cheap Trick or if Taylor doesn't do Eagles I think Elliott would do 'Heartache Tonight' fairly well.
Chris - Maybe 'You shook me all night long'
Katharine - These Dreams by Heart, Invincible by Pat Benetar,
Paris - This Time I Know It's For Real - Donna Summer
Just a few thoughts, and just doing some quick reference on songs from thsoe years.