Be Honest: Do you think I can get into Duke, UPenn, Northwestern, or Columbia University? If so..which one?

Isn't the maximum weighted gpa 5.0? If so then your 4.0 weighted shows a lack of rigorous courses-but you said you took all honors and AP so I honestly doubt it is only 4.0. Your extracurricular activities look good. The only thing is that your SAT score probably won't be able to carry you into Columbia, but the others look good. I'd say definitely Northwestern and Duke, if your SAT goes up a little more Penn isn't out of the question.