Dang, when I read the title of this posts, I thought it was going to be about blondes, brunettes, and redheads...
Since it isn't, I do as you all do, and include headers, footers, and then content. I use <div> tags, and have been pretty good at using tableless css design, to boot...
I like to use constants for my meta information and my body ID's. Then, I echo them out in my header. I like using <body id="home"> the body ID attribute, so I can determine to show sub-navigation on specific pages or hide them via CSS, or I can use PHP conditionals to include sub-nav info in my header file based on the body id... you get the idea...
My latest layout is something like this:
<?php
// include functions / start session:
include('functions.php');
// define meta info:
define('TITLE', 'Page title');
define('KEYWORDS', 'keyword, keyword2');
define('DESCRIPTION', 'page description here...');
// define body id for css classes specific for page
define('BODY', 'home');
// include header
include('header.php');
?>
<div id="main"><!-- html code here //--></div>
<?php
// include footer
include('footer.php');
?>