I don't find a lot of diference in F1 and the IndyCar Series on road and street courses. On some of the natural road courses like Road America there's a little room for passing, but that's about the only differene. I've probably been to about a dozen Detroit Grand Prixs, but I'm not sure I'll ever go to another one, but if they came back to Michigan Speedway I'd go every year until I was taking that dirt nap.
On the other hand you put Cup, Nationwide, truck series, and even ARCA on a road course, and that's exciting racing. Has a lot to do with the fenders and the beating and banging.