Wikitravel recommends using the local variant of English for all destination articles. This means:
Don't worry if you're not familiar or comfortable with the local variant of a destination: just write in the style you're accustomed to.
The only case in which it would make any sense to go through an article to standardis(z)e the orthography would be in preparation for a star nomination or for offline publishing. If you are preparing to do this for any destination outside of the four regions listed above, it is best to first discuss which variant you are going to use on the article talk page.
If the destination has no history of using English and no clear preference for the variety to use, we prefer American English spelling. This isn't because American English is somehow better or to stomp on the rights, heritage, and cultures of other English-speaking countries. We just need to pick one default spelling style for consistency. Below are reference guides for American spelling:
Occasionally proper names do not follow local spelling conventions. These words should not be changed -- the proper name should not be mangled to conform to Wikitravel's spelling rules.
It can be helpful to other editors to use an HTML comment to mark incorrect spellings which are preserved in proper names:
* '''Café Art's<!-- sic -->''' - a popular cafe in the Paquis neighborhood of [Geneva].