We just came back from our son's PIR he graduated on 1/14. We stayed at the Ramada and planned on taking the shuttle, but ended up driving instead. It is much easier to have your own car as you can take your Sailor right away with you and not have to worry about catching the shuttle back. Also If you take the shuttle, its still a 15 to 20 minute walk once you get there because they are not permitted to drive you in as far as you can in your own car. However, if you drive, I would leave no later than 6:30, earlier is better to get there in plenty of time to find a good seat. The traffic is bumper to bumper going into the base, so make sure to give yourself a good amount of time. Even though the Ramada is only 4 miles away, it took us an hour to get there because of graduation traffic. Unfortunately, one of the Ramada shuttles broke down last week and so the families that were on that shuttle ended up getting there after ceremonies had already started and had a hard time finding a seat.
When you drop your sailor off, you can pull into the the base right at the first entrance their is the Navy Exchange store where you can park and go in and shop, that is what we did when we dropped him back off after liberty.
I hope that all helps. I know it sounds stressful, but really, as long as you leave early enough, you will be fine. Enjoy the graduation, it is so amazing to see these Sailors graduate! ;)