I found a mix of GW and CC worked best for us, I started on GW to wean him off needing me right next to him. Then we moved onto CC, - but my version of it!
If DS (17m) wakes up in the night i go straight in, give him bottle of water to drink and change his nappy while he drinks, then I cuddle him til he finishes the (small) bottle.
Then its back in his cot, if he seems wakeful I stand by the door and do one round of goodnight room (an abbreviated version of his go to bed routine) Then i leave the room, if he is crying I go back after 10 minutes. I start by saying Shhh, but DO pick him up or offer more water etc if he keeps crying but only until he is calmer and snuggly (not asleep but not screaming).
Then leave again, etc etc.
Its a personal judgement thing, there are times when he works himself into a state and me being there makes it worse so I don't do nursery rhyme or cuddles. But most nights a drink and a cuddle is all he wants. I feel thats reasoanble - partly because he was a TERRIBLE sleeper from 8 - 13 months (5 times a night wakings and screamings) so one wakeup and back to sleep within 30 minutes is pretty good. ALso I figure at udner 3 they don't wuite get nightitme/dark/no mum and DS cna't yet manage bottle completly on his own. So if he wakes up and is thirsty (which happens to adults too!) He needs me to help him out.
You say that quick reassurnace isn't wokring - could it be nightmares? the times that the 30 minute drink and cuddel thing doens't work for DS is nightmares, he gets himself in an awful state - we find that change place = change state for that. I takre him onto the landing and then we go back into his room but I put his globe light on. He sits and stares at it compeltly mesmerised and then falls asleep.
One bad night I had to leave it on by his bed all night bu he did go back to sleep.