We did the laying down at bedtime with our toddler and that seemed to open a new can of worms (of course). One thing that helped was something my sister told me...our son doesn't like complete darkness in his room or the door closed so we would tell him at night that if he got out of bed, we would turn off the light or close the door. He didn't want that to happen so he would stay in bed. Tears were shed, so you do need to be strong. We did do the warning system so it wasn't on the first time of getting out of bed.
For example: Gets out of bed the first time, just put her back in. Second time, warn her that you will either close the door or turn off the light. Third time, do one or the other and then if she cries you can give in and tell her that next time that is what is going to happen for sure. Fourth time, follow through.
As the days go on, you can give fewer warnings.
When he started falling asleep on his on and in his own bed, then he would still wake up in the middle of the night and come in bed with us. We ended up putting a sleeping bag next to our bed and when our son would come in during the night, we told him he could sleep down there. We did tell him before he went to bed that if he needed to sleep with mommy and daddy, that he could sleep in the sleeping bag. It was a tough couple of nights to get it started and not much sleep on our part (because every time he would get in bed with us, we would put him back in the sleeping bag), but afterwards it was well worth it. Just remember which ever approach you use, don't give in because it will be like starting over. It may be a tough week, but just remember you are not the only one that is going through this and the end is in sight. :) And if you do try the sleeping bag thing, maybe do it when you have a couple of days off in a row so you can either nap with your daughter during the day.
One more thing, after our son slept in the sleeping bag the first time, we praised him and made a HUGE deal out of him sleeping in the bag.
Hope you find some good things that will help you!