do you think an IRL date could afford them a chance to build grandstands on the start/finish line and maybe one or two other areas? what are the rest of the facilities like (ie. parking, garage area, roads in and out, etc.)?
besides, it's not like Watkins Glenn or Road America are chock full of them. the only reason Sonoma has as many as they do is because it is also an NHRA facility when NASCAR and the IRL aren't there. same with Portland.
part of the beauty of a road course is the ability for fans to camp in one turn all day or move around as the day goes on.