I don't think you should add either, interests have no merit on a resume and like you said the GPA will be noted regardless. Unless you want to mention something like "Summa Cum Laude" or anything similar, then that's ok I think.
... think you should add either, interests have no merit on a ... advised to add not only interests, but travel as well, as ... />
ANd tons of people put interests on job resumes. As an ...
Add your GPA if it's good (above the median for your target schools).
Add a Personal section with some interests if you have room. If nothing else, it gives AOs something to ask you about in an interview.