Main observation: Big arenas blow soundwise. No revelation there, but Queens of the Stone age were both very loud and hard to hear. Chili Peppers were better, but the upper deck seemed to get zero bass.
Show wise, they were great. Extremely tight playing for over 90 minutes. John Frusciante gave advice on crowd surfing "the object is to kick the least number of people in the head."
Sean was on the main floor -- a $45 ticket, which is absurd to me -- and came home soaked in other people's sweat. Festival seating is a crowd tragedy waiting to happen. From the upper deck there were parts of the main floor so tightly packed all you could see was the tops of people's heads, and waves of motion swirled around through them -- a shove at one side of the crowd would travel all the way through.
Trying to remember if moshing was ever actually cool ... mmmm...no. Maybe in 1976 at CBGB's in a Ramones show.
T Shirt prices were absurd -- 27 to $40. No shortage of takers. So ... there were about 5000 people there, each of whom paid a minimum of $24 for their ticket. -- $120,000? Probably sold at least 1000 $30 T Shirts for another $30,000. So $150,000 for one event. Nice work if you can get it.