Display all custom post type posts and order them by an optional meta_key

<?php
// query posts
$query_property = query_posts( array( 
     'orderby'    => 'date meta_value' // orderby date AND meta value
) );

// First loop
$query_feat = $query_string.'&meta_value=on&meta_key=property_featured';
// Offset for second loop
$query_all = $query_string.'&offset=3&meta_key=property_featured';

// First loop
if ( $query_feat->have_posts() : while ( $query_feat->have_posts() ) : # etc....
    // do stuff
endif;

// Second loop
if ( $query_all->have_posts() : while ( $query_all->have_posts() ) : # etc....
    // do stuff
endif;
?>