Allow me to echo Doyle's points. Having served 5+ years as a Marine officer, I was faced with a similar question. There were numerous attractive options available to me had I decided to stay in (FAO, Congressional Fellowships, Masters Programs, etc,) but as we both know, a lot comes down to luck in the military and there are no guarantees whatsoever. So I had to make my decision to stay in or get out independent of these potential "gold mines". Ultimately I decided that I wasn't being challenged much anymore as a Marine, and at just 28 I had grown physically and mentally tired of the old games. Not to mention the fact that I am engaged to a wonderful and independent woman whose own career would surely suffer if I continued to move around every 3 years.
So, you have to decide based on the merits alone of staying in or getting out. If you still feel the calling to serve your country if called upon, you could enter the selected reserves (or whatever the Army equivalent is), as a nice middle ground.
For what it's worth, if you do well on your GRE, I think you'd be extremely competitive at any of those schools. You have plenty of time to take them, and it is a test that is easily mastered with some brute force studying.