I ran into the spelling conundrum when writing my articles for The Penguin Opera Guide. I discovered that most of the American venues in which the works (mostly musicals) I was writing about premiered spelled their names with the "Theatre" spelling. So I duly used the spelling used by the theatres themselves. And my British editor duly corrected them all to "theater," because those venues were, after all, American, and therefore that's how the word must be spelled.
I discovered that there's so consistency on these shores, given the inclination to feel that British spellings are classier and just plain better.