Friday qualifying is usually pretty sparse attendance. That's why it my favorite day to go. You see everybody run and you're not crowded.
Saturday is much more crowded...and I heard today that Sunday is very close to a sellout.
Thanks I guess I'm used to the Mile Hi's in Denver where all three days used to be sold out. I always preferred Friday also for the same reason plus I have several friends who tour in Super Gas and Super Comp so I get to see them run too.