My kids are currently 7, 12, 14 and 16. We've been "unschooling bedtime" since the get-go. These days generally the two younger ones go to bed at about 11:30 or midnight. The 14yo now goes to bed at 1 or 2 a.m., though for years he was the earliest of the bunch, at about 10:30 pm. My 16yo has been a night-owl since the day (or night, actually!) that she was born, though tonight she was tired and went to bed before 10. Often she's up until 2 or 3 a.m.. We used to have pairs of kids sharing bedrooms. Currently only the 7 and 12-year-olds share.
The main issue has always been dh, who takes 24-hour on-call and has the earliest start to his day, so he likes to be in bed by 10 pm and really values whatever uninterrupted sleep his work allows him. The party line here has been "your right to stay up late ends where daddy's right to sleep begins." In other words, if staying up past 10 interferes with dh's sleep, it's a problem. If you can stay quiet enough that you don't disturb him (or any others who want to sleep) that's fine. Same deal with the bedroom-sharing kids: you need to be quiet enough coming to bed that you don't unduly disturb your roommate. As cheery said, it's all just part of being in a family: respecting others' needs, comforts and wishes.
Bedtimes are one of the things we discuss regularly at family meetings: just to make sure that everyone is aware of ways in which their own choices about bedtimes might be negatively affecting others in the family. Often there's no problem, but it's good to discuss it anyway, just so that we're aware of how our choices could be affecting others.