Using “Read More” link with custom excerpt

This should remove the <p> tags, but leave the styling by replacing the paragraph tag with a <span> class:

function all_excerpts_get_more_link($post_excerpt) {
    return '' . $post_excerpt . '' . '<span class="readmore"><a href="'. get_permalink($post->ID) . '">' . 'Continue Reading &raquo' . '</span>';
}
add_filter('wp_trim_excerpt', 'all_excerpts_get_more_link');