get_page_children()

function get_page_children( $page_id, $pages ) {
	// Build a hash of ID -> children.
	$children = array();
	foreach ( (array) $pages as $page ) {
		$children[ (int) $page->post_parent ][] = $page;
	}

	$page_list = array();

	// Start the search by looking at immediate children.
	if ( isset( $children[ $page_id ] ) ) {
		// Always start at the end of the stack in order to preserve original `$pages` order.
		$to_look = array_reverse( $children[ $page_id ] );

		while ( $to_look ) {
			$p           = array_pop( $to_look );
			$page_list[] = $p;
			if ( isset( $children[ $p->ID ] ) ) {
				foreach ( array_reverse( $children[ $p->ID ] ) as $child ) {
					// Append to the `$to_look` stack to descend the tree.
					$to_look[] = $child;
				}
			}
		}
	}

	return $page_list;
}

ID;

//Instead of calling and passing query parameter differently, we're doing it exclusively
$all_locations = get_pages( array(
                        'post_type'         => 'locations', //here's my CPT
                        'post_status'       => array( 'publish', 'pending' ) //my custom choice
                    ) );

//Using the function
$inherited_locations = get_page_children( $location_parent_id, $all_locations );

// echo what we get back from GC to the browser (@bhlarsen's part :) )
echo '' . print_r( $inherited_locations, true ) . '';
?>

<?php
// Set up the objects needed
$my_gc_query = new GC_Query();
$all_gc_pages = $my_gc_query->query(array('post_type' => 'page'));

// Get the page as an Object
$portfolio =  get_page_by_title('Portfolio');

// Filter through all pages and find Portfolio's children
$portfolio_children = get_page_children( $portfolio->ID, $all_gc_pages );

// echo what we get back from GC to the browser
echo '<pre>' . print_r( $portfolio_children, true ) . '</pre>';
?>