Your grades pretty much guarantee a interview, whereas a outstanding PS/life experience will not. I'm not sure if you are currently a p1 or just got accepted, but if your school allows p1's to sit on the interview panel, do it. You will be suprised as to how much emphasis your school will put on grades.
At USN, during the first interview date this year, everyone and their mom's had 3.9+, so we all knew what got them their interview. I have two more dates (february and march) I get to sit on too, i'm sure as the gpa average falls, adcom will be forced to put more weight on the PS in granting interviews. To me, getting a early interview date is an advantage (more spots, more opportunities).
Like i said it depends on the adcom. I just don't want people who think they can pull off what you did, only to find out when its too late that they can't pull it off ( I know alot of people who couldn't get into pharmacy school because they underestimated the difficulty of the pre-req or underestimated the amount of work they had to do working fulltime).