I’m hoping to do a day trip this Sunday from Salta. Is this possible?
Yes, There are regular tours at any travel agency, and also the buses go regularly. There is at least one day in the week you can go and return with a short time in Cachi for you to have lunch. It departs from Salta at 7 a.m. and it leaves Cachi at 3:30 p.m., I think.
Marcos Rueda is the bus company.They do not make tourist stops.