I may have entered Argentina by plane, but my departure via the scenic bus ride from Mendoza to Santiago (Chile) was worth the extra transit time.
In Mendoza, I bought my bus ticket on Andesmar a few days in advance for just $35.90.
By comparison, flights cost several hundred dollars, and you miss some of the most beautiful landscapes outside of Patagonia.
The ride lated about 7 hours, including the time it takes to pass through Argentina and Chilean Immigration.
The highway passes by Puenta del Inca, but this natural geologic bridge can't be viewed from the bus. My photo below was taken a few days earlier on a separate tour.
Another point of interest you can see from the bus, if only for a few seconds, is Aconcagua (6,960 m), South America's tallest mountain.
I lucked out in that it was a beautiful, clear day. Thanks to the GPS on my iPhone, I was able to snap a photo of the cloud-shrouded peak as we passed it by.