Elqui Valley or Atacama
 

We will be in Buenos Aires and in Chile in early August. In Chile, we will be in Santiago and Valparaiso. then we have three days and would like to do some traveling and star-gazing in Chile. Would you recommend that we go to the Elqui Valley (La Serena, Vicuna) or to Atacama? Unfortunately, we will not be there on a Saturday, when some of the big observatories are open. We will be with our 16-year-old. Also, open to any recommendations in any of those locations. Thank you!