680 - Have the "Should I Retake?" Dilemma

Scored a 680 last month on the GMAT but with a weak Quant score (in the 67% range, if I recall correctly) and I am now trying to figure out if I should try again. I will be applying to Yale, Cornell, Duke and a couple of lesser tier schools. The skinny on my background: *Pol Sci Degree, Business min...