Merzouga is the most known location close to Erg Chebbi, a dune field located in South West Morocoo. Erg is the perfect kind of desert, a lots of sand making never-ending waves. In Erg Chebbi, dunes are specially tall, the highest one is 884 m.
Because there are no roads, just tracks (pistes), the only safe way for finding places there is through coordinates, so instead of standard address the hostels and touristic attractions in Erg Chebbi include coordinates for drivers using GPS devices.
When I was in Morocco in 2001 our local guide didn't need GPS. He drove 140 km/h our small rented car through tracks full of big stones and poteholes. We had a lot of baraka (luck, in Arabic) to arrive safely to our hostel.
Morocco is a very affordable and safe destination. In a couple of hours of flight from Europe you run completely away from the Western World, enjoy the delicious tagine and Berber hospitality.
As you can see in the mini-panoramio below, the landscape in Erg Chebbi is amazing.