I have yet to see the movie "300", but I have read the story of Leonidas and can't help myself from thinking what a sad, heroic and immortal story it is. I love the name because of the history about king Leonidas.
This name is so pompous and elaborate, it's ridiculous. I can't imagine calling someone Leonidas (lee-oh-NIE-das). They'll most likely get called Leo anyway, so why not go with Leonard, Leonardo, Leon, or just plain old Leo?