Southern Thailand consists of a long peninsula and many islands.  Movies like "The Man With the Golden Gun", "The Beach", and recently "Survivor: Thailand" have been filmed in this area.  The extreme south connects with Malaysia and is mostly Muslim (I have yet to go that far).  Phuket, Krabi, and the surrounding areas are a big draw to beach goers.  It is more expensive and a little more 'touristy' than other areas.