It depends when your ds has to get up in the morning. On a school day, what time do you have to leave the house? Also, does your ds have a set waking up time of his own? if he always wakes at 7.00 am no matter what, then IMO it's fair for him to go to be at 8.00 ish. If his body clock is not so set, and he will sleep longer in the morning after a late night, then IMO it would be fine for him to stay up later.
My son is just 10 and goes to bed around 9.30 pm on school days, but then he doesn't need to get up till about 8.00 am. At the weekend he stays up later but also lies in in the mornings. I keep a running review of his waking times, so if he's really tired in the morning and won't stir himself when it's time for school, he knows he will be sent to bed earlier the following evening. Pure cause and effect and IME less easy for him to argue against it. Also, he can't bring what his friends do into the discussion - it all boils down to how he is in the morning.
He stays up only if he is nice to be with though - if he is naughty or being irritating, he knows he will be sent to his room. I find it a good way of getting him to behave well. He sees staying up as privilege, and as long as he is behaving nicely, he is lovely to be with, so it's no strain on dh or I. Making him go to his bedroom earlier, and having a long argument about it, would (for me) be more of a pain.
I guess you have to decide what you want the most - less fuss from your ds in the evening but a later bedtime and hopefully a boy who's nice company, or more fuss from your ds but more pure adult time for you.
At age 8 I guess my son's bedtime was from 8.00 to 9.30 on school days, and from 8.30 to 10.30 at weekends. Where we are, some clubs for older kids don't end till 8.00 on school days,( judo from 7 - 8 pm , cubs from 6.30 to 7.45 pm) so the organisers obviously feel parents are not all putting their 8 year olds to bed by 8.30 pm each and every night.