Travel and International Etiquette
There are vast differences in international cultures, and the only way to know what si appropriate in any given culture is to study it, specifically.
However, the author differentiates between low-context cultures like thee US (individualistic, logical, focused on the present, direct communication, factual, competitive) and high-context cultures like Asia (group-focused, relationship-oriented, intuitive, indirect, traditional, and ritualistic).
In general, etiquette is dictated by location: if a person from the US goes abroad they must conform to the standards of the other country's etiquette. If the foreigner comes here, it is their duty to study, understand, and conduct themselves according to the standards of our culture.
However, it is a mark of a good host to be respectful and accommodating of the standards of a foreign culture on one's own soil. Do not call attention to their minor mistakes, and do not expect them to understand the nuances of our culture.
If you have to travel long distances, it is acceptable to dress comfortable - but be aware that there is a difference between "comfortable" and "slovenly." Chances are, you will meet other business people while traveling, striking up casual conversations in transit.
Likewise, courtesy in transit is very useful: you will have an easier time of dealing with airline personnel and government employees, who can help you out of a jam or, if the mood strikes them, help you into one.
As with etiquette, travel, tipping, and the protocols for dealing with people along the way will differ greatly depending on where you're going - study in advance.