I tried this, but I'm getting unexpected results. Do you use one language only?
Starting with a browser configured with "Italian", "English (United States)", and "English" in that order (Chrome isn't letting me remove either English), this is what I'm seeing:
If I have it only, I get Italian.
If I have it and es, in that order, I get Spanish
If I have it, es, and en, in that order, I get English.
If I go to a page I know is localized, Google for example, I see Italian.
Is this what should happen? I would like to be able to offer users content in their own language rather than one I choose for them.