I suppose experiences can vary widely at airports, but it seems to me that LAN has been getting better, even on the domestic side. Lately there has always been a greeter at the lines in the terminal who will direct you to the 'comodoro' line if you mention oneworld status. There is also a special separate check-in area for premium passengers in SCL. There are no domestic lounges anywhere in the system, though. Many airports in the LAN system do have Diners Club and other credit card and Priority Pass access.