I think a C-style for loop would be appropriate here:

  my @names = ('rita', 'sue','bob', 'daisy');
  for (my $i = 0; $i < @names; ++$i)
  {
    print $names[$i],
          '     ',
          ($names[$i+1] || ''),
          "\n";
  }
[download]

rita     sue
sue     bob
bob     daisy
daisy
[download]