Need advice on getting 20mth old to sleep in big bed....

Hi...

Just wondering if anyone out there has any suggestions on how to get my 20mth DD to sleep in her new big bed, she had always been a fantastic sleeper (sleeping through the night from 6 weeks). We have had to move her out of the cot as my second DD is getting too big for the bassinette and needs the cot shortly.

At the moment she seems to go to sleep quite easily for her daytime sleep but after 4 nights it is taking at least 2 hours to get her down for the night time sleep (and last night I was up from 2.30am - 5.00am before I had enough and put her back in the cot and I don't even think she went to sleep then!)
We have tried taking her back in everytime she got up but I lost count on how many times I had to take her back and I think she thinks it is a fun game as she would come and grab my hand, smiling and say 'back to bed, mummy' and tug me back to her bedroom. We have also just sat in the hallway outside the door where we can see each other and eventually after an hour or so she would doze off. We have also tried shutting the child safety gate that we put in her bedroom doorway and hoped that she would get tired enough to want to go back into her bed herself but she would just scream and ask for cuddles. Should we try leaving her with books (which she loves) and a night light on?

Are we trying to many different strategies? Do we just perservere with one strategy for at least a few days? Did a particular strategy work for you? Does having a bed railing maybe intice them to stay in bed?

Sorry for the long speel and the loads of questions, I know I need to be patient and it is only early days but any advice would be helpful.

Thanks