It's largely a matter of personal preference, but an important consideration is that using site.com will mean any cookies served from site.com will also be serv

It's largely a matter of personal preference, but an important consideration is that using site.com will mean any cookies served from site.com will also be served on any subdomains. For more reading on the subject: http://www.phpied.com/www-vs-no-www-and-cookies/ http://www.phpied.com/www-vs-no-www-and-cookies/ "Basically you should always use www if you're planning to use any other sub-domains and you want them cookie-free."