One of the most incredible natural sights I've seen is Sossusvlei. If you're visiting, you're probably (hopefully) spending two or three days to really take everything in. It's an area where sunrises and sunsets can be magical, and the skies are so dark you'll see the night sky the way it's meant to be seen.
One popular way to toast off a sunset is at Dune 45. Compared to some of the taller dunes, it's only about half as tall at 170m (558 ft). Even if that doesn't sound that tall, climbing up a sand dune where every step you take, your slide down a bit, is not to be underestimated. Until you've tried, you just don't realize how hard it is. Oh, and did I mention there will be sun, and lots of it, beating down upon you? It's still totally worth your efforts, just so you know.
In any event, this is Dune 45. It's a beautiful dune, and I enjoyed watching the sun set from here, although it was a little too popular the night I went. My guide said it was the most people he had seen there, and that means there were about 20 people. It is, the middle of a desert after all, but a wonderful place to a have a drink and snacks as the sun goes down.
Sand formed into a dune that is roughly 5 million years old inside the Namib-Naukluft National Park, a UNESCO World Heritage Site.