Temples, food, people.
Thailand is the only country in Southeast Asia never to have been colonised, and you can feel it: an unbroken monarchy since the 13th century, Buddhism everywhere, a cuisine and culture like nothing else. Bangkok, capital since 1782, mixes the golden temples of the Grand Palace and Wat Pho, one of the world's oldest Chinatowns and ultramodern towers. Further north, Chiang Mai, former capital of the Lanna kingdom, kept its walls, its hundreds of temples and Doi Suthep overlooking the city.
What makes the country wonderful is first its people: incredibly kind and patient, even when language is a real barrier. Then the food, from the street to the night markets, probably the best I've had on any trip. And the religious festivals, when the whole city moves around the temples. Superb landscapes on top.