My first started in a bassinett in our room, and very briefly moved into her crib across the hall. She very quickly changed her mind and made it apparent that she would not be sleeping alone. I fought for weeks trying to nurse her to sleep and lay her down, and it was miserable for all of us. At 3 months or so, we put her in our bed and never looked back. We had her crib sidecarred for a while, and then she had a small bed on the floor next to ours for a bit, and she slept in her own room for a few weeks a while back, but at 4 yrs old she is still in our room. (She is my high-needs baby; there was some very early separation at the hospital and I think that's why she still has some separation anxiety.)
By the time DS was born, we no longer even owned a crib or bassinett. At first, DH slept on the sofa, DD next to me, and DS on my chest. It worked out well because when DS woke and needed a diaper change, I just stepped out to the living room and DH was right there to help if I needed it. (Which I did, at first - I had horrible tearing and could barely get around.) Once my mom went home, we moved the full size bed from DD's room/guest room into the master. We have a queen size bed and a full size, both on the floor, right up next to each other. Megabed! It's seriously like 10 feet wide, it's awesome. For the most part, the kids and I sleep in the queen bed and DH next to us in the full, but often DS rolls right up next to DH in the other bed. I'd love to have the two kids together in the full bed, still in our room, before the baby comes, but we'll see. The new one always sleeps on my chest, well away from siblings, for a few months, so I think I can make it work if the other two are still right with me.
Honestly, I'm of the belief that baby should sleep wherever everyone gets the most sleep. For us, that's always been with us. I do believe that if you have a strict timeline for when baby should be out of your bed, that maybe co-sleeping isn't for you. I think all the "my son slept with us and we NEVER got him out of our bed" stories are from people who tried to push it well before their child was ready. Just like anything, I think weaning from co-sleeping should be on the child's terms. (What I'm saying is if you think I'm nuts for having 3 kids in my bed, one of them nearly school-age, maybe co-sleeping isn't for you. :) And that's ok, too. Whatever works for you. )