That's where my tack diverges wildly from yours! Completely disregard this if it really assaults your ideas, here's what I do with my child in my situation:
If DS won't go down, I let him go and play off some steam. I'd rather have the 'malarky' than spend two hours trying to get a non-sleepy child to sleep. Cos I could be doing things in that time! Granted, my child is now walking and can entertain himself better, but I did this from very early on. I wasn't going to be the bunny getting strung out pushing the proverbial uphill. My thinking was that whilst I know that this kid should be in bed, the kid had no such reasoning and was only going by what his body was telling him, which was invariably 'not tired yet'! I am the one who is capable of adjusting my habits around the kid, but I know that DS is not about to work around our expectations of him. He just won't, I know my kid - he is just way too engaged with his environment. Other kids are a lot more cooperative to their parents, from what my friends report (although, they also spend ages trying to get kids to sleep, so I don't know just how well their system works!). So, I work with him, instead of the other way around. My next kid might be very different.
DP was very skeptical of this for a long time and wondered why I wasn't trying to do what other parents try to do. He now sees that it would be futile and end up in us getting stressed that he's not comforming, and DS being upset because we're not listening to him.
Now that he's older, if he's not ready to sleep and I am completely at the end of my tether, I've lately taken to getting him ready for bed (with all the cues that it involves - changing into PJ's, turning lights down, putting sling on, feeding him in sling, putting 'night nappy' on etc), and lying him down next to me anyway. If he really doesn't want to be there, I let him go and I stay in bed! Now that he's more mobile, I figure that he knows where I am. If he really wants to play, he will. If he's just overtired (usually on a day when we've done heaps out of the house) he'll walk out of the room, down the hall, realise I'm not following, come back and ask to be helped into bed with me. Then he'll sleep.
So, whilst my whole spiel here seems to many people like I'm just letting him run riot, what I've been working up to all these months of his life is to recognise when he's had enough and when it's time for bed. Sure, mostly he needs help to get to sleep, but it's slowly starting to emerge that he can listen more to his body beyond just the 'hungry' or 'clingy' messages!
Sorry for the dissertation, but this is what I mean by getting back to basics. I mean letting go of 'norms' and getting back to listening to what your child is telling you, even if they don't see it.
Yep, I get comments from people who say "I wouldn't do that", and I think "well, that's fine, cos you don't have to, he's not your kid". If my ideas don't suit, ignore this whole post. You know for yourself what you are comfortable trying. I was comfortable to give it up to him to tell me what I needed to be doing. When I see that he is finally properly tired, I go through the cues again, and he gets his bearings again.
DP realises now that there is method to my madness. It doesn't have to be anarchy, it doesn't need to be highly regimented. Routine does not have to mean 'schedule'. One is flexible and quite portable, the other is not as easily taken on holiday or away for a couple of nights, and a change of environment can render a 'schedule' useless for a child.
Sorry, I really don't want this to sounds like a sermon!!
I thought it might be useful to read about someone else's experience, even if you adopt none of it. My way doesn't mean you lose control of anything, it just acknowledges that there are some things you don't control, you just work around it