Where there's a difference, we prefer Commonwealth English spelling to American English spelling. This isn't because Commonwealth English is somehow "better," but because we need to pick one spelling style for consistency.
If you are from America and use "harbor" or "aluminum" or whatever, that's fine. We want your contributions and your work, so don't worry so much about spelling. But editors may come through and switch those over to Proper English, just for consistency.
Sometimes proper names have words in them that are spelled differently in American and Commonwealth English, or just misspelled altogether. These words should not be changed -- the proper name should not be mangled to conform to Wikitravel's spelling rules.
However, referring to the proper named thing in the generic should be mangled. Examples may be clearer:
- Molson Center is the centre of hockey in Montreal.
- The harbour in Sydney is called Sydney Harbor.
- Ten tonnes of aluminium a day are extracted from the Ten-Ton Harbor Aluminum Center.
- Joaquin Miller's home, "The Hights," rests on the heights of the Oakland hills.
See also: List of common misspellings