According to a recent study by the World Economic Foundation, these 30 countries are the most approving of the tourism industry as well as the most welcoming to foreign visitors. Locals will be more than willing and patient to help you in the right direction should you need advice. As a comparison, the U.S. ranked a lowly #102 out of 140.
One interesting correlation that pops up over and over again is that the countries that typically rank near the bottom in terms of economic development and median income conversely rank at the top for friendliest. They are often the most eager to share with strangers and promote the cultural, rather than monetary, wealth of their country. Even better for English-speakers, in places where the language isn't well known, the people are oftentimes even more willing to be patient and assist you, even if it's a struggle to understand what you want sometimes.
Southeast Asia and the Pacific seems to be one of the friendliest places in the world, as multiple countries from the region made it onto this list. New Zealand, Fiji, The Philippines, Cambodia, and Laos all rank highly in visitor surveys for being considerate, selfless, and well-meaning to foreign visitors.