Steve is dead on balls accurate. (What else is new)
The only thing I want to add, which I always do when the "Importance of summer seminar" comes up" is:
Everyone interested in the air force academy SHOULD APPLY for summer seminar in December of their Junior Year. If you get selected for it; great. You'll have the opportunity to see the academy first hand. Summer Seminar is more of a tool for YOU the applicant to get a taste of what you MIGHT be getting yourself into.
If you don't get accepted for summer seminar, that's OK too. But it is still VERY IMPORTANT that you apply for it. Why? Pray Tell!!!
In most states, you are simply a name, number, application, etc... when applying for your congressional nominations. Your senator or representative can only submit 10 nominees for each slot they have open. So you are trying for 1 of 10 slots, out of possibly 40, 60, or even 100 other applicants trying to get a nomination. You MUST STAND OUT!!!
Well; congressmen love to see committment, determination, passion, etc... If you "APPLY" for summer seminar, it shows you really want the academy. It doesn't matter that you get accepted or not. If in your nomination application/essay/etc... you squeeze in the point that you applied for summer seminar, your congressman knows you're not just applying for a scholarship education. You actually want the academy enough that you were willing to go to Colorado springs for a week and check it out. (If accepted). This helps you stand out. Your congressmen know that not everyone can get accepted to summer seminar or the academy. But, if they can only give 10 nomination, an they have 20 applicants, and hypothetically all 20 were pretty equal when it comes to academics and extra currilcular activities, the deciding factor many times to make a final choice, can come down to things like volunteering for summer seminar. Volunteering for Boy/Girl state. (if your state allows applying).
Acceptance to Summer Seminar won't affect you receiving an appointment, but it "COULD POSSIBLY" have an impact on you receiving a nomination. And you can't get the appointment without a nomination. I suggest that you always apply for summer seminar. If you get it; great. If you don't; no big deal. But simply applying shows committment and determination to your congressmen.