Huacachina is the largest natural oasis in South America. Though it is no longer natural, due to many hotels constructed and tourists coming to that area, the oasis remains a unique place to visit.
The area is not big and there is not much to do other than the dune buggy and sand boarding which only take few hours. So you can just take a daily trip from Lima or stay for one night only. Do not stay longer than one night, it will be boring.
But, is it worth to visit? Absolutely!