I still prefer LAMP. One trick to improving cache on LAMP is converting or caching files into HTML. I know there are a number of templating engines like Smarty out there that will do just that, but what I mean is actually converting dynamic parts of the site that only change when an admin writes new content. Convert those pages into static HTML files when the admin adds new content, etc.
For example, a number of ecommerce website run off shopping cart systems that use a database. Why not have them convert into a HTML version of the site after the admin adds new products, edits products, ect. That would take a huge load off the server and database.