Definitely agree, that if you can afford the time and money to go to A-Day, as well as all of the Parent's weekends, you should. We were fortunate, if you want to call it that, that we only lived 2 hours away. We were down at the academy for everything. Unfortunately, it was also a curse. During the first 2 years, when cadets can't "Own/Possess" a car, my son would call us for almost every 3 day weekend or similar holiday so we could pick him up and bring him home. Sometimes with additional friends. But that was OK too; I guess. Although, it was funny as hell when he and his roommate "From Madagascar - off the coast of Africa" came back to Wyoming for Christmas. His roommate didn't know the PLANET could get that cold. It was like watching the movie "Cool Runnings" when the Jamaican Bobsled team landed in Canada in the winter and saw cold/wind/snow/ice for the first time.
But all in all, the more you can do, especially the FIRST YEAR, the better it will be. Not necessarily for your cadet, but for you as parents. Your cadet has 4,000 others near him/her that are in the exact same boat; and ARE or HAS gone through exactly the same thing as them. Your cadet will be just fine. You on the other hand don't have anyone else around who understands. And for what it's worth, the 4 years at the academy are going to SCREAM BY. You're going to wake up and s/he will be graduating. Then, they are off to their real first base. Then, you'll be lucky to see them once a year. While on active duty, I say my parents about once every 3-4 YEARS. I actually saw them more when I retired. They would come to wyoming for a visit; kids graduating high school; graduating college; etc.
So enjoy your time with your kids as much as you can now. Just make sure they have the space they need. And once they are at the academy; DON'T tell, suggest, remark, or opine on anything about the academy/military UNLESS THEY ASK!!! This is THEIR LIFE NOW. You can think they are "Off to College"; but they aren't. They are emancipated, legally responsible, adults who have to make their own decisions and deal with what's in front of them. So, if you can make it to A-day as well as all the parent weekends, definitely go for it. If not, then at least make as many parent weekends as possible. Especially the first one.