First off, congrats on the great score! I was actually in the same boat, scored a 690 the first time and felt I could have done better. I took a break from studying and realized I wanted to take it again, so I cracked the GMAT books and 7 months later I went in and scored a 710. Not a huge difference, but breaking the 700 barrier I think will make a big difference.
If you feel you can do better on Quant, I would recommend taking it again, but set a goal for yourself and set a date now. I found that I was very un-motivated until I actually scheduled the date and paid the $250.

Look at the pros and cons:
Pros - Most top schools let you choose your best score to use, so if you do worse, then at least you have a 690 to fall back on. Also, you get a second chance to send all scores to 5 schools (since all scores are reported the second time around), so that'll make up for not sending the 690 out the first time. Lastly, if you do break 700, it will show schools that you are determined to improve and compete to get into a great program.
Cons - more GMAT studying

Best of luck whatever you do! I know what you mean by being done with GMAT studying!