Chile is 4,300 km long and its two poles are as different as anything in the catalog. San Pedro de Atacama sits at 2,400 m with the Tatio geyser field at 4,320 m and the altiplanic lagoons above 4,100 m. You gain and lose 2,000 m most days, which is the real physical demand. The dryness is why ALMA and Paranal are there and why a moonless night over the Salar de Atacama looks the way it does.
In the far south, Torres del Paine sits at the eastern edge of the Southern Patagonian Icefield in Última Esperanza. North of it the Carretera Austral runs roughly 1,240 km of mostly gravel through Aysén, stitched together by ferries, past the marble caverns of Lago General Carrera and the Queulat hanging glacier. Chiloé is a separate world again: sixteen UNESCO-listed wooden churches, palafitos over the tidal channel, and the only place on earth where Humboldt and Magellanic penguins nest side by side.
Country-level constraints that decide whether a date is possible.