Back in June we had Marcie and her kids stay at our house. We've started to let the kids (minus Nathaniel) sleep together in one room and they do OK. We let them have some talking time and then we go up when it is time to go to sleep. After that there is still a little talking and getting up to go to the bathroom/get water/procrastinate going to sleep but once they are asleep, they sleep well!
Before bedtime my kids wanted to have s'mores with Megan and Amelia. Everyone took making s'mores very seriously as you can see from the pictures.