The question to ask yourself is whether you think you would stand out in a competitive applicant pool, given your background, before getting around to your GMAT score. If the answer is yes, then your GMAT score shouldn't be a problem. A 660 is strong enough to tell the schools that you have the ability to succeed in their classrooms. Great, but about 80% of their applicants have that ability. What they're really looking for are your points of differentiation. If you have that before getting to the GMAT, then you should be okay. If on the other hand, you're simply not comfortable with where you stand in terms of the GMAT and you have time, then take it again.
In our book Your MBA Game Plan
, we talk specifically about selling yourself to three of the four schools you mentioned (no Georgtown). Based on your line of questioning, I think you'd really benefit from it. You should consider taking a look at it.