If money isn't an issue and you are okay with the extra time for secondary essays, there is no reason not to add the extra schools. There is a definite element of randomness to applying to medical school and you never know when a top ranked school might like something in your application.
Duke's secondary is a beast so I'd leave that one out. UCSF might be a bit too much of a reach with a 3.8/33. Granted, your chances are decent everywhere, but since you're applying to mostly top schools, I'd leave those ones out. Northwestern, U of Mich, and U of Chicago are your best choices IMO.