They should fall in with their classmates and wear the cap and gown, not expect special treatment.
when I open the door for a lady, give up my seat for somebody older or a lady, or even help with a package when somebody needs help, I'm sure they're not "expecting special treatment"... but I'm extending a courtesy because I feel that it's deserved and that's the way I was brought up... and am bringing up my son up the same way. As a person that cherishes women, the weak that need help or just a fellow human, I'll extend a courtesy.
Those that chose to serve in the Armed Forces should be cherished and their sacrifice should be honored. If wearing their dress blues or Army full dress uniform is making them feel special... well I've got news for you. They are special.
As a society we should have those that serve held up as examples of what is honorable, good and decent in our high school graduates. Our society requires as the price for freedom the lives of some of it's men and women.
It's a small "price" to allow something as trivial as wearing his Dress Blues.
It's also a great recruiting tool. There is nothing like the sight of a Marine in his dress blues to make the young girl's heart quicken and the other guys jealous.
I guess if you really want to freak the high school out have these "boys" show up at graduation...