Taking a Spanish class is never a bad idea but it isn't going to stand out on your transcript or anything. Lots of applicants have a semester or two of Spanish under their belts. Now if you were fluent in the language that would stand out and look great on an application. If you want to take the class and it satisfies a requirement, take it.
It shouldn't really matter, although I was asked how my spanish was during an interview last year. If there is a large spanish speaking community where you are, it may be viewed as a plus, but in reality I don't think it will matter either way.