From what I've seen in some of the published skill challenges ... insight is tied well into Etiquette. If nothing else, Insight is used in many skill challenges as the "find out what to avoid".
Insight fits well, since etiquette isn't necessarily a charisma based skill, charisma (and diplomacy) can be improved by good etiquette, or used to make up for bad etiquette. Wisdom, on the other hand, seems like something that does work, especially in terms of intuitive/improvised etiquette. Wisdom is tied to common sense and being perceptive, aware of people and your surroundings and the like ... which does seem what ettiquette is about, being respectful, paying attention and such. Now, knowing specific facts like "in this culture, you need to do X ..." history does include customs as part of what you can remember with a succesful check.
So, basically:
History can tell you about specific customary ettiquette of the region, insight can give you, well, insight into avoiding any faux pas, and diplomacy can be used to attempt to overcome your bad ettiquette.