My daughter and I did the one day trip. No complaints, it was a great experience. We left at 6 sharp, arrived about two hours before the race was supposed to start which meant we had to hustle a bit to stand in line to get the paddock passes, but no big deal. There was a bit of uncertainty about when the bus was leaving because of the rain, but we only left about 40 minutes late and that was because of the traffic, our bus driver said. Not really any concert fans I guess, but no one wanted to miss the bus.
Got back at IMS about 10:40, and back in Terre Haute before 12:30. I would definitely do it again; avoiding the congestion on I-94 is a big plus for me. We had a great driver on Bus #1 by the way. Many thanks to Graham & the Andretti organization for making this trip possible.