front-page.php

<?php

/**
 * Force Full Width Layout
 *
 * @author Bill Erickson
 * @link http://www.billerickson.net/overriding-options-and-meta
 *
 * @param string/array $meta_value
 * @param int $post_id
 * @param string $meta_key
 * @param bool $single
 * @return string/array $meta_value
 */
function be_home_full_layout( $meta_value, $post_id, $meta_key, $single ) {
	if( '_genesis_layout' == $meta_key )
		$meta_value = 'full-width-content';
		
	return $meta_value;
}
add_filter( 'get_post_metadata', 'be_home_full_layout', 10, 4 );