Display Alternative Theme based on Role (template.php)

I was wondering if anyone has been able to setup alternative themes based on role?

I've tried with the following code (in my template.php):

   global $user;
   if (in_array('Author/Staff Writer',$user->roles) or $user->uid=='1') {
      $vars['template_file'] = 'page-admin';
  }

In the code above, I'm determining if an author or administrator is logged in, and if so display the admin theme.
Unfortunately, it only works for admins and not for those logged in as users under the 'Staff Writter' role.

Anyone have any suggestions?

Thanks in advance!
-wOOge