personally, i say take the shuttle to PIR unless you don't mind waiting in a line of cars.
Here's something else to consider - the weather!! If you're PIR is coming up soon (or even the next few months), then it could be a mighty cold walk. As far as I know the shuttles do not actually go onto the base, but will deliver you to the gates outside. There's already a bit of a walk from the parking area to the building for checkin and then another walk to the ceremony hall. Walking thru the gates isn't a whole lot farther, but in -7 degree temps (before the wind chill) it will make a difference! And the shuttle vans will still have to deal with the traffic.
We arrived at about 6:00 a.m. and were the 8th or 9th car in line to get thru the gates. The traffic backed up behind us very quickly. We also stayed at the Navy Lodge, which is the closest hotel to the RTC entrance.
Something to keep in mind is the roads get really slick around here in the winter, and seems people going to PIR don't always know how to drive. I have been rear ended going to work, two different times by people going to PIR.
I would recommend taking a shuttle. You still get to see your loved one.
If you're not into getting up at 5 am to get in auto line (then after you get out of your car you have to wait in line at the parking lot too). I would take the shuttle. There is only one line instead of two. And the walk is shorter from the gate to the PIR building, than from the parking lot to the PIR building - but only by a little.
The shuttles/taxis drop you off just inside the gate, in the small parking lot. That's where you or your recruit can pick up a taxi later to go back to your hotel.
We didn't bother with a car at all. We got a weekend train pass ($7 per person) and took the train to Chicago. It was MUCH nicer than taking a car.