If you're considering joining CAP, because you think it's going to "Look Good" on your academy application....... Please don't do it. Same goes with anything. Sports, scouts, JrROTC, Band, etc. You do these things because you WANT to. You do these things because you have a passion to do them. Not because it makes your application look better. And trust me; if you're doing any of these things for any reason other than because you "WANT TO", then you won't truly succeed in them, and probably won't like it.
This is not to say that you don't like CAP or have a passion to join it. Maybe the whole Mitchell award is just a "Side Benefit". But even so, don't worry about it. The majority of academy cadets weren't in CAP, JrROTC, Scouts, etc. This is not to say that these things don't look good on your application. But so does being in sports, in the band, class officer, member/officer of a club, volunteering, working, etc. You have to find the "PASSIONS" that you have; pursue those passions; and excel at them in leadership positions. That's what looks good on an academy application. It doesn't matter WHAT it is you're involved in. As long as it shows you are passionate about it and excel. Anything else, is simply trying to "Fill the Squares"; and that WILL show. Best of luck.