ALTIPLANOS.
Almost any major mountain range or altiplano in the world. For accessibility the Himalayas in Nepal and, more so the Alps. For extra wow and isolation theKarakoram, the Pamir highway or Kyrgyzstan 'the Switzerland of Central Asia'. The Switzerland of Europe isn't bad either.
ISLANDS.
Jamaica/Dominica (and much or the Caribbean), Fraser Island (Australia) and Santo Antão (Cape Verde).
US NATIONAL PARKS.
Yosemite, Alaska, the Grand Canyon & Bryce Canyon are our favorites.
GREAT BARRIER REEF.
Actually, Australia's reef is a little overrated (sorry Aussies) due to recent destruction. If you have the chance -- go to the Philippines or Borneo where you'll feel like there might be too many fish.
The Red Sea is fantastic as are the waters off Thailand, Belize, Malaysia and Indonesia.
FJORDS.
New Zealand's fiordland, or similar examples in Norway, Iceland or Chile.
SOUTH AMERICA.
Patagonia and the Torres del Paine National Park, Chile and Bolivian salt flats (Salar de Uyuni) plus Altiplano
Expensive, but amazing.
Antarctica, Galapagos Islands, Pamir highway, Iceland and Ngorongoro crater (or any East African safari).
Honorary mentions.
Iguazu Falls on Brazilian/Argentinean border
Namibia's Namib-Naukluft National Park plus Skeleton Coast
The Egyptian White Desert
Ha Long bay, Vietnam