Retake Advice - Do I stand a shot at a full scholarship with a 720?

It is a bit presumptuous as you are assuming you can get into those highly competitive programs. However, I don't know the rest of your capabilities so perhaps you will easily get in.

Top 10 is hard work getting in, let alone getting a scholarship. Scholarships to top 10/top 20 are usually not given based on the GMAT score (though the complete package is taken into consideration) and if a school feels you would not attend otherwise and would like you to - the reason they give scholarships is not because you are so great but because they want to build a strong class (being a little pragmatic perhaps).

If you have time (I would not take more than a month),and no other major issues in the application, my suggestion would be to retake to fix your quant score a bit - get it to 49 at least; don't think you need to go to 50 though. When a quant-oriented person takes the GMAT and gets a 67th percentile - that does not look too good in terms of effort invested. Hopefully you could bump up to 740+ to impress the adcom a bit more, but it is all should be taken into consideration as a full package. If you have other bigger fish to fry, you may use your time there more effectively towards your application success.