A common misconception that I see often is the idea that a traveler should see Australia and New Zealand together in one trip. Unless you have months to visit and limitless budget, its tough to see even the highlights on both countries. Keep in mind that Australia is the size of the USA. Can you imagine believing that you can see the entire US in a week or two plus another country too? Remember that Australia has the Great Barrier Reef which is the size of the western US coastline.
