You might also want to consider the total number of takes. It is usually meaningless, unless you have taken the GMAT 5,6,7 times, but it might, just might, count for the uber-elite admission processes.
It really depends on how bad you need a higher score and how hard your goal program is to get into.
A 720 nailed on the third attempt after a 600 and a 640 COULD be valued less than a first attempt 720 and labeled as a lucky day instead of a positive progression.
At least this is what I gathered from the retake thread, being in a similar situation.
should-i-retake-gmat-thread-retaking-gmat-strategies-83339.htmlCheck that one out if you can, and good luck!