Moving meta boxes in admin

You can remove the default post tags metabox and then add it again in the desired location, ex:

add_action( 'add_meta_boxes', 'move_tags_metabox_location', 0 );
function move_tags_metabox_location(){
    global $wp_meta_boxes;
    unset( $wp_meta_boxes['post']['side']['core']['tagsdiv-post_tag'] );
    add_meta_box( 'tagsdiv-post_tag', 'Tags', 'post_tags_meta_box', 'post', 'normal', 'core', array( 'taxonomy' => 'post_tag' ));
}