I am a fan of I-Day. It's the last time you get to be the powerful Mom/Dad to your kid. You get to witness bravery in all those kids who are taking a leap into cold, dark, uncertain, and (apparently) unfriendly waters. I liked I-Day more that PPW.
Things to do: First walk around down-town Annapolis, AND DON'T BE SHY. If you see an 18-20ish yr old trailing a parent/s or just a college age guy/girl: "Are you here for I-Day?",that's all you have to say and the conversation will flow effortlessly . So many great families, and plebes-to-be; all anxious to talk about who they are, where they are from, why they are there, what they expect, what they hope for. Most seem anxious to maybe make a friend that might be needed in the immediate future. On the parent side of this, besides getting to know some great people, there's the strong possibility you will pick up a valuable tidbit or two that will help with the upcoming year. If there were ever a time to be outgoing, this is it!
My wife was "non-plused" by DD's decision to attend the USNA right up to I-Day. Those couple of days on the streets of Annapolis before I-day she got to meet our DD's ship mates and families and it turned her around totally: to bad it happened before visiting the Mid-Store. Conversation with strangers will never come easier, or be more rewarding.
Other stuff:
1) I enjoy the small museum on campus, across the street from the chapel; worth a visit.
2) Take a guided tour of campus out of the visitors center; other plebe-to-be families will be doing this too.
3) Walk campus purposefully, paying attention to details, and locations. Knowing the layout of the place gives you just a tiny bit of "power" over your situation and at some point you are going to have to find classes.
4) Same-same for walking Annapolis and finding the Whole Foods, Bed Bath Beyond, shopping center. It just reduces uncertainty and the task of finding these places when you do need to get something off the yard.
5) Strong 2nd to Capt. MJ's visit DC suggestion. Big fan of the Native American Museum. I honestly think DD visited that specific museum 10--12 times while she was at USNA. There are Lots of interesting smaller museums and galleries in and around DC too. No lines, interesting more focused looks at history and art, (just do a quick Google).
6) Back in 2015, a 2c parent suggested that we scope out a cool private spot, close to Bancroft where we could take our DD/DS when we got them back for our 1hr at the end of the day. I wasn't altogether clear on why we needed to do it, but we found a spot that seemed out of the way. When we got DD back she was composed, but clearly "holding it together". We got to our spot--and DD lost it. She had no complaints, no doubts, she wasn't scared, she didn't even know "why she was crying". It took about 5mins, she got that big chunk of emotion out, squared herself away and pushed ahead relaxed. She hadn't broken down publicly (not sure she would have let it go if she hadn't had some privacy). Looking back I'm pretty sure it was the sheer enormity of the change undertaken in that single day. Mom, Dad, Home, Sister, ....almost every aspect of her life had changed in a matter of hours, and none of it would ever be exactly the same again. That's a pretty big bite to chew off at 18. Anyway, for us the "find a cool private spot" was good advice, so I'm passing it along.
Good luck to you all!!!!!!! You've made such a great choice. I truly believe you are attending the best undergraduate institution/program in the world. When it comes to academics, leadership and ethics the USN is "eating it's own cooking" with the USNA, and it shows -----you'll see.