Our itinerary:
From Buenos Aires we intended to take the overnight bus to Tilcara but someone had stomach troubles. Instead we took the quick but less interesting airplane to Salta then a short bus ride to Tilcara.
From Tilcara we took the bus back to Salta then it was by bus over the Andes to San Pedro de Atacama in Chile.
From Atacama we took a bus to the airport in Calama, then a flight to Santiago.
After Santiago we took the bus to Valparaiso. Finally we returned to Santiago and then flew home.
Travel tip: We found some Chilean businesses, like the airline that flew us to Santiago, don't accept non-Chilean credit cards. At least they didn't accept them online when we tried to book plane tickets. But we found they would take PayPal, so that served as a fallback.