We have the same issue with our 3 year old and have a 2nd on the way. My wife refuses to let him cry it out so every night he goes in his own bed and wanders over at some point. We tryed a couple different beds and none worked. If one of us sleeps over there with him, he will stay. That is the plan when the new one comes. If we keep him in his bed for the 1st 2 hours, he usually stays put.
I know a lot of folks with the same issue. Maybe read a book by Dr. Sears who advacates a family bed!