I would highly recommend re-taking the GMAT, as your GMAT + GPA is how they primarily discern if you're up to the rigor of their program. I was waitlisted and ultimately denied last year. During my feedback conversation I was told that they were impressed by by 3.53 undergrad GPA from a Public Ivy, and didn't doubt I could do the work, but that my 650 GRE was merely 'within the range' and 'improving my score, if I had time, would strengthen my application and let the committee know I was serious.' I had 6.5 years of work experience which I was told was on the 'low end' - especially if you don't have a few direct reports.
I'm not sure where you received your graduate degree, but if it's from a notable school/respected department with a fair amount of rigor, you're likely fine on that front. Retaking the GMAT can only help you strengthen the AdCom's perception of how serious you are about the program, and that you're willing to put in more work to succeed. A waitlist-->accept student I met during a class visit told me he retook the GMAT and actually got the *exact* same score. The admissions caller that phoned him to tell him he was off the waitlist said that seeing him make an additional effort to improve his application, even though his score didn't improve, sent a strong message to the AdCom. Just some food for thought!
660 is my highest score. I tried a couple more times to increase my score, but unfortunately 660 was the best I could manage. Hopefully taking the GMAT 3 times should count for something in terms of effort. I have a grad school degree in engineering from a public university in a southern state. Not Ivy league by any means.