Good replies. I have my PPL and I was not selected for USAFA. My reason for getting it was that I want to be a pilot, not just to get into USAFA. Getting your license takes an awful lot of time, money, and work. You could spend that time, money, and effort on things like improving your test scores, boosting your GPA, etc.
Like the last 2 replies said: Don't get your PPL as a "USAFA Application Booster". Only get it if you really want to fly; then, by all means, put it on your app. But don't expect magic.