If you are applying to a top school, you should DEFINITELY take four years of language even if the “required amount” is 2 years. Schools want to see your commitment to a subject and a great way to show this is through foreign language.
Here’s what a few colleges have to say on this:
http://www.thecollegemoneyguys.com/should-you-or-your-student-take-4-years-of-foreign-language/