Friend of mine was David Cassidy's godson. We were given a tour of these places under the stands along the main straightaway in the late 70's. Cafeteria tables lined with women and men counting money! It was UNREAL, like a scene out of the Soprano's.
Congrats. Are you coming just race day, or a longer trip? Definitely check out Charlie Brown's pancake house on Main Street while you're there. The line can get pretty long race weekend, but other than that, it isn't bad. There's a ton of Indy history on their walls. Also, if you're going to be sitting in one of the stands without a backrest on race day, the backrests that the speedway rents for like $10 are a great buy, and you just leave them in your seat when the race is over.