I am fully aware I posted an image of a dune just a couple of weeks ago, but please bear with me. Because not only do I really like this image I took in Namib-Naukluft National Park, it is also a great example of how useful longer focal lengths can be in landscape photography.
The dunes of the Namib are absolutely massive (the second highest in the world) and tower up to 300 metres tall. The vegetation visible in this image might look like low shrubs, but you are actually looking at full-size trees. In order to convey the sheer scale of the dune, I shot this image from the street several hundred metres away and used a long focal length (300 mm on APS-C, 450 mm full frame equivalent) to compress the fore- and background, bringing the trees and dune closer together. I also made sure to take this image late in the day when the sun was already nearing the horizon to benefit from the soft, warm afternoon light.
So contrary to what many think not every landscape should be captured with a wide-angle lens, and tele lenses can actually be immensely useful in landscape photography.
Taken with the Pentax K3 and HD DA 55-300 WR lens at f/8, 1/320th sec. and ISO 200 at 300 mm.