Thanks again for the advice.
I'll start out by saying that crowd management outside of the venue sucked. They opened the gates 1 hour before the show and the line to get in was probably 400 yards long, and growing, when we arrived. To make matters worse, the drop-off point for the shuttles was right in front of the gate, so you had people crashing the line as soon as they got off the shuttle. There were plenty of personnel walking around, but it seemed like they couldn't be bothered to do their jobs.
As for the concessions being a money grab, you were right on target. We paid $24 for two hamburgers with fries. Not that bad and we expected to pay that because of the venue. However, the burgers we had were terrible. The meat was cold and the fries were too. They did have Stella Artois on tap though, which was nice considering the only other choices were Bud and Bud Light.
The lawn seating was really nice, but packed. If you take anything other than a stadium seat or blanket to sit on, you are in trouble. The incline is severe enough that you wouldn't be able to sit in a camp chair.
We went to see The Doobie Brothers and were really impressed. They played most of their well-known songs and were really a lot of fun. Chicago, on the other hand, I could have done without. The wife and I left about halfway through their show and hiked the mile or so back to the parking lot so we could beat the traffic.
All in all, not a bad little Saturday night. We would consider going there again for a concert, but skip the hamburgers next time. :-)