Moving this to Stacy's forum area. Stacy is our resident expert on MBA admissions and would probably have more to say about your case.

My two cents: if you have stellar work experience and a high GPA from a great university, you'll likely be a competitive candidate with your 690.

Good luck!

I believe I answered this earlier today?
For the schools you are targeting, a 690 is a bit below average. That said, many people are admitted with a 690 or lower. I always feel that it is best to enter this process with as many things going for you as possible. Certain things are outside of your control - if you had a low GPA, there is nothing you could do to change it. With the GMAT, you can retake and if your score decreases there is no harm; if it increases you are a bit better off. If you feel that you CAN increase your score, it certainly would not hurt to retake. However, a 690 is not going to break you, and a 750 is not going to be your key to success. It is just one piece of the equation. I know this is not a black and white answer, but one does not exist. If I were you, I would think about whether you really feel that it is within your abilities to improve. If so, I would retake, and do so by end of July. If you do not feel that you can improve, there are plenty of other elements to focus on and many other areas that will contribute to you being successful.
Good luck!