Can any parents provide insight on R-Day? Should we arrive the day before, leave day of or stay the night?
Your new cadet will have a morning check-in (if I'm remembering correctly they started ~6 am last year and went until 10 am or so). If you are flying, you probably want to arrive the night before and plan extra time for traffic (unless staying very close by), to get through security, park and walk to check-in. Parents/family can stay with the new cadet while waiting in line, then will proceed into an auditorium where there will be a welcome and introductions (can't remember if it was by the Sup). Then the 60/90 second good-bye...literally. That will be the last time you talk to your new cadet until A-Day in August.
You can spend the rest of the day touring West Point (one of the few times you can visit Constitution Island), buy t-shirts etc, listen to briefings and possibly catch a glimpse of your new cadet going before The Cadet in Red Sash (I did!). That evening (6 pm?) there is a formal parade and introduction of the new class of 20xx. You will not get to talk to your cadet or even get close, but make sure you have your camera to begin your Waldo hunting and arrive early to the seating/stands on the Plain. It will be crowded. Unless you can get a flight out that night, or want to drive home then, your best bet is to spend the night. You will be exhausted, physically (from walking up & down all those stairs and hills) and emotionally. It was very hot & humid last year.
A-Day is a whole different experience and your cadet will likely want to leave post as soon as possible after the formal parade/acceptance into the Corps of Cadets -- then sleep in a hotel, shower alone, change into civies, go to a movie, spend time with family, relax!....