I totatlly agree with Knarf. My son and I went and really had a great time. For the parents the information was great and the tour of the engineering/math/science building was awesome. I was so impressed by the facilities and state of the art equipment. I was amazed to see the plebe chemistry labs with only 20 students per class (only 10/class in the Organic Chemistry lab) taught by the professor and not by a grad student or TA! They also had an admissions briefing for the parents, a tour of the yard, panel discussions with current mids and current mid parents. We got to watch noon formation and the formal parade on Friday afternoon. We did stay and go to the football game on Saturday and had a great time but there were torrential rainstorms that made watching the game a little tough to enjoy. Navy did win against Wake Forest!
I highly encourage parents to attend if they can. If you can't that's okay the candidates were well taken care of and had their own briefings, meetings, tours, etc.
As far as transportation, I spoke with a few candidates who came by themselves and they were able to get the shuttle to/from BWI. When you get the confirmation letter from USNA it will give you the numbers for the shuttles and the times. We got there around 5pm Thursday (we drove there) and my son was done around 10:30 a.m. on Saturday morning. Make sure if your child wants to buy souvenirs that they go to the Mid store (it is right next to Bancroft Hall), as long as your student is with their hosting Mid or tells them that he/she is there for the CVW they should let them shop there. They have a much larger selection than the visitor center and the prices are much better.
Also, my son brought homemade cookies and other treats for his hosting Mids and it was very appreciated.