I have been each year and I sit with the Central Indiana Region / PCA. We have a block of seats in "J" stand which is at trun 1. There are still tickets available throught the club. Also provided is priortiy parking if you drive your P-car and a police escort to the track. Check out info here:
http://cirpca.clevertech.net/events/usgp/club_corral.asp
There will also be a dinner the night before the race sponsered by Porsche of North America.