Mine are DS nearly 9 and DD nearly 7, we aim for lights out at 8 during the week and anything up to 9.30 on Fri and Sat.
DS goes to Cubs on a Tues and doesn't get home till 8.30 so obviously later that night. He doesn't need to be asleep at 8, but goes at the same time as DD and reads in bed. He also gets up by himself at 6.45 whereas DD has to be woken at 7.30 for school.