gmat retake?

I would not suggest retaking in December. First, it will likely not leave you enough time to complete your applications well, which at this point is far more important. Secondly for the schools you suggested, a 690 is pretty good. So, take your shot! and leave the GMAT alone.

Do you think it's worth writing a personal statement/optional essay explaining why my quant scores are so low? I'm really very concerned that they'll not want to admit based on that. I'm not sure how to put this, but I'm betting that there are a lot of other white american males that are applying with higher quant scores.

As Jon pointed out, you would be better without retaking it. The only reason I say this is because, you will compromise other parts of your application.
If you retake your GMAT on 24/25 Dec. you will be left with 10 days to write essays, talk to recommenders, fill in online application, collect your documents etc. And all this during the new year.

All your concerns are genuine. Bluntly speaking, yes your quant score is low and you know that for yourself.
What you can do: If you are hell bent on applying this year and want to apply in more than 1-2 schools, start with your applications right away. Address the quant score in your optional essay and the steps you will take to enhance your quant skills (some class/online course etc.)

Saying that, there are may people who get in with that score. Your overall score is pretty good!

Or

If you can delay applying a year (very unlikely:)) or you feel you have a great story and might have a good shot in R3 then do retake your GMAT.
There was a very recent vid titled "should I never apply to R3" as part of 1000000 posts celebration. you may want to go through that.

Good luck with your apps.

We recommend not taking the test again -- your scores are high enough and your quant abilities can be demonstrated through other aspects of your candidacy.

You need to start focusing on preparing your application. As your scores are good enough, you have to make sure your essays, recommendations, interviews, etc.are top notch. These are not easy to accomplish as candidates invest a lot of time, energy, money and resources into preparing strong applications that showcase their candidacy in the best light. This is much more work than most people expect.

Kimberly Plaga
Senior Admissions Consultant
Manhattan Review

Thank you so much for the responses. I did a lot of forum-hunting and was spooked by the emphasis that a lot of programs appear to put on quant.

I am also thinking about changing slightly to the following schools in light of these facts:
-Duke Fuqua (reach, but my dream school)
-USC Marshall
-UC Irvine Merage
-Penn State Smeal (undergrad alum / safety school)
-UC Dublin Smurfit - (I currently live in dublin and this is the best b-school in Ireland)

The only thing is that I'm still thinking about applying to UNC Kenan-Flagler. It looks like they put a lot of emphasis on GMAT, though. Not sure whether it's worth the effort. Any advice would be appreciated!

UNC looks to be in the right range for you, IMO.

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