conditional rewrite rules

So far I tried the following, without getting what I want:

add_filter('rewrite_rules_array', 'my_rewrite');
function my_rewrite($rewrite) {
	global $wp_rewrite;

   	$category_rules = array(
        	'concerts/' => 'category/concerts/',
        	'venues/' => 'category/venues/'
    	);

	$concert_post_structure = $wp_rewrite->root . "concerts/%year%/%monthnum%/%day%/%postname%/";
	$venue_post_structure   = $wp_rewrite->root . "venues/%postname%/";

	return ( $rewrite
		+ $category_rules
		+ $wp_rewrite->generate_rewrite_rules($concert_post_structure)
		+ $wp_rewrite->generate_rewrite_rules($venue_post_structure)
	);
}

What I get is this:
* concerts/ and venues/ don’t work
* concerts/year/month/day/postname shows all concerts, what I would like concerts/ to do
* Same for venues/

Any help is appreciated, guys.