Structure - how much is enough?

As Indian parents raising American kids in suburban Seattle, there are numerous issues we grapple with. Chief among those is the issue of a schedule and structure for the kids days. Growing up in India, I do not remember a strict bedtime - my parents lugged me and my sister along to parties and gatherings. Often times, we would fall asleep at the hosts house with all the other children there - a forced sleepover. We had a great time! It was my favorite thing to do.

Here of course, things are different. When I first had kids and started to surf some parenting sites and boards, I was baffled by sleep times of 5:30 PM, 6:00 PM and so on. The kids were in bed at the middle of the day. Suffice it to say, my co-sleeping kids never went to bed at 6PM, unless it was a late nap.

7 years later, I still have angst around schedules. We have a rough one and we stick to it more closely during school days but on summer vacation, we've let things slide. Arjun loves to read and sometimes he is up at 10:30PM, still reading. I've gone in and switched off his nightlight even though I hate that being done to me. I know he needs his sleep and I know kids in his class are asleep at 8PM. Today, we stuck to the 9PM bedtime - OK, 9:15 PM but it has been a nice and quiet house with the kids in bed. I hope we can keep this up! Now I need to see if they hop out of bed by themselves tomorrow morning - that would make the schedule so worth it.
Wish me luck in keeping this up - a little structure is good for all of us. Even I can see that now - all my crazy sleeping arrangements as a kids, not withstanding.
In turn, can I ask that my friends not drive me out of the house as soon as the clock strikes 6:30PM so that the kids can get in the bath? Please??