C.S.
My oldest son is almost nine, and he goes to sleep as soon as his head hits the pillow. Darn him ;)
My daughter will be six next week, and she's a completely different story. Her bedtime used to be nine (she had afternoon pre-k and kindergarten). She would lie awake until around midnight, singing quietly to herself, getting up to go to the bathroom, tossing around, kicking the wall, playing with the cat, etc. This year, she has been so tired that she could barely do her work at school. I moved her bedtime earlier, to 7 pm, and now, when she goes down, she drops to sleep within about 20 minutes. I had a few little problems trying to get her father to comply (we're divorced, and I'm remarried), so, when she comes home on Tuesday night, it can take a bit more time for her to fall asleep.
The key for her seems to be consistency and getting her in bed before she's over-tired. Even if things are chaotic around here in the minutes before bed, as long as she's IN BED by about 15 minutes of bedtime, she drops off pretty quickly. I don't know if that helps you any, but good luck! Bedtime is one of the most frustrating parts of parenting, IMO!
Good luck!