I would say, take a look at what some travel agents offer as tours for the amount of time you plan to be there to see what is typically done.
For example, this is the agent I am working with
http://kulansatours.com/tourlist.html
But of course there are many, many others. This place was highly recommended to me as well
http://www.qwestdestinations.com/inb...i-lankan-tours