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 English variant of a destination article: just write in the style you're accustomed to and somebody will probably come along later and correct it - that's one of the benefits of wiki editing!
If the article concerns one of the very few destination countries that has no history of either colonial occupation nor using English and no clear preference for the variety to use, we prefer US English spelling if you're starting a new destination article.
This isn't because US English is somehow better (although US spelling usually is shorter) or to stomp on the rights, heritage, and cultures of other English-speaking countries. We just decided to pick one default spelling style for consistency in new articles.
If it's an existing article that already has consistent spelling using one variety, then please don't arbitrarily change it to another spelling variety without discussion. Many of our non-destination articles were written in Commonwealth English and should not be arbitrarily changed to the US variety.
One longstanding Wikitravel foible you should be aware of is the consistent use of traveller and travelling (rather than "traveler" and "traveling") in many articles.
Although it's preferable to use a consistent variety of English for all of one country's destination articles - and certainly throughout the same article - it may not be the best use of your time to go right through an article to standardis(z)e the spelling unless preparing for a star nomination or for off-line publishing.
If you are preparing to do this for any destination outside of the regions listed above, it's best to first discuss which variant you are going to use on the article's discussion page.
Where appropriate, try and use a commonly understood word or phrase in preference to one that has a different meaning because of national differences.
For example, instead of writing "Peter tabled his nomination"
(which will be understood as "...withdrew his nomination" in the USA but as the exact opposite in much of the English speaking world), write "Peter withdrew his nomination" so that the phrase will be universally understood.
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:
* Joaquin Miller's home, "''The Hights''"<!-- sic -->, rests on the heights of the Oakland hills.
Plural forms should not have apostrophes (unless the result of applying this rule is confusing).
For US English spelling: