You should be able to get a decent spot, no problem. Even out toward the highway, there is a pretty new shower house, so it's not a long walk wherever you are in the camp. The showers are also improved over what you saw that long ago. The busses circulate continuously, so the wait isn't too bad, although the ride can exceed 10 minutes depending on where you get on the route. The comment above on the bike is accurate.
As far as off-site, I think you miss the whole atmosphere. The outdoor movie theater is something new to you, and great fun in the evenings. It's a huge screen and great sound system. Bring a chair or blanket for the grass.
Not to think in stereotypes, but if your girlfriend likes shopping, there is an outlet mall on the west access road across from the field. I got a great Columbia winter coat for $80 that had been three times that, that I've been wearing for years.
The show prices are certainly higher now, and many criticize the event for being too commercial, but to the credit of EAA, at least they do make improvements every year. You're gonna get hooked all over again.