Thought I'd stick my experiences in here - I'd love to be able to give you the answer, but nothing we're doing here seems to be working either.
My LO (18 months) is taking up to an hour to finally pass out when we get her into bed both before her nap and her bedtime. I'm wondering whether it's partly because she's been at home with us all over Christmas, and I'm sure we don't exhaust her as much as a day in nursery does (it only really started a couple of weeks ago) but I suspect it's also largely to do with how active and alert she is, and how quickly her talking is coming along at the moment.
Current routine is wake at 8am (far too late for us to get ready to get out of the house to go to work/nursery) nap between 1.30 and 3pm (again too late a start really, but she won't sleep before half one, sometimes even two, regardless of when we start the routine) and sleep at 9pm (although right now (9.15pm) she is still awake, even with Daddy's best efforts!)
Believe it or not, we started getting her ready for bed at 7.15pm this evening, so we're currently been trying to get her to sleep for two hours!!
The thing that I really don't understand is that we tell her 'it's time for bed soon' a couple of times, and then when it is time, she makes her own way upstairs. We have a bath, some milk, and a couple of books, and then we put her into her cot, and then she wriggles for up to an hour. She never really screams, she never seems that upset - she just takes FOR EVER to finally pass out!!
Daddy has just come down, and she seems to have finally dropped off. I'm glad to say that BW has helped me once again with this, even if I haven't got the ultimate solution. Just knowing there are other people out there in the same situation, and that's it's not that my LO is insane, or I'm being a useless parent, has helped me immensely. So thanks again to all you wonderful people who are willing to share their thoughts and experiences.