Siblings (not) going to sleep in the same room

Happy Australia Day!

This is a problem I'm having, and I'm betting someone else is having similar problems, and I know some of you will have good suggestions:

I'm in a two-bedroom apartment, so my boys (who are almost-8 and 4.5) share a bedroom. This is fine, except that they have a veeery hard time falling asleep in the same room. They laugh together, or they fight, or they just talk and talk and talk. I sometimes come in every five minutes to tell them to be quiet, and it doesn't help. If I lie down with one of them they'll stop talking, but then I wake up in a puddle of my own drool at midnight. (It's just like having a 2-year-old again!)

If I let one of them fall asleep in my bed, it starts a major fight. If I let them both fall asleep in my bed, they don't fall asleep.

I am sure that part of the problem is the late schedule: By the time I get home from work and pick them up from their dad's and walk home and make dinner and they eat it, it's 8 o'clock. So they have half an hour before they have to put on PJs and brush their teeth and go to bed. But then they don't actually fall asleep until 9:15 or 9:30 or even 10:00 some nights because they just can't seem to settle down and stop interacting.

I know this isn't enough sleep for them, and that mornings would be better for everyone if they were getting more sleep. But I can't put them in separate rooms to fall asleep. Any ideas?