This is a difficult question as Sri Lanka has a lot to offer to a traveller. (Please read about a detailed article on travel in Sri Lanka) As a travel professional, I have designed a tour programme of 31 nights which had only Jaffna & Sigiriya for 3 nights but rest are either 2 nights or single night stays. Therefore, I know for a fact that you can even have a few months of a busy travel schedule visiting various places around Sri Lanka.