Well, the transition isn't complete yet, but here's what we've done. When ds was 2yo, we nightweaned him. After that got all settled down, we put the crib mattress on the floor in our bedroom. I put some cute little animal pictures around it on the wall. And we made a big deal about that being his bed, and we would sit in there and read. I woud lay there to nurse him to sleep, but sometimes he would want to go to sleep in our bed, and we were fine with it.
Now he goes down for naps and for the evening in his bed, but wakes up at around midnight or so and comes into our bed. We are going to get a twin mattress so that it's easier for us to lay there with him when he wakes up at night, rather than bringing him into our bed.
So we did a gradual transition, which we are still in the middle of, but it seems to be working well overall. I think the key was not forcing it and making him feel "kicked out." I'm due in July with our 2nd, so am confident that by then he will be happy being in his bed all nght. I will miss him though! Especially now that he's nightweaned, it's so sweet to just cuddle up with him in our bed, and when he wraps his arms around my neck I feel like just might die from love overload!