My wife and I did not plan on co-sleeping before our son's birth.
We had set up a Pak 'n Play with bassinet insert in our room, right next to my side of the bed for nighttime feedings. For as long as it seemed necessary, we would keep him near us, eventually transitioning to the crib in his room.
But, as so often happens with babies, what we planned did not match what worked for our son.
He was a healthy nurser and was up every two hours, just as the books said. I didn't find it that hard to get up whenever he cried, but I would have to concentrate very hard on fighting off sleep during each nursing session. I find it very ironic that breastfeeding is connected to the production of prolactin, a hormone that, yes, creates a feeling of contentment, but also induces drowsiness--and new mothers just don't need help in that department.
And then, although my son would quickly drop off to sleep in my arms, he immediately woke up whenever I put him in the bassinet. I would sit in bed and hold him, trying to wait until he was completely asleep, so that I could gently lay him down without waking him. But, oh, the exhaustion. I often fell asleep with him on my chest. My main fear was that I would drop him, yet I found that if I slid back down into bed and settled him on my chest, just so, he seemed quite safe and the two of us slept for longer periods of time.
My wife and I finally made a conscious decision--or admission--that we were co-sleeping. We rearranged our bed a little bit, and our son took over the middle of the bed.* He started most evenings in his bassinet, but moved into our bed at the first feeding and stayed there. Everyone slept much better.
But we rarely shared this information. When I either mentioned that our son still woke up frequently or even hinted at our 'unusual' sleeping arrangements, I got all sorts of unsolicited advice. The crowning moment came when I was at lunch one day. A colleague asked how my son was sleeping. I admitted that he rarely slept more than 3 hours at a stretch;** I may also have said something about him sleeping best in our bed. My colleague immediately began extolling the virtues of crying it out. My principal latched onto the bed thing and began lecturing me: "You just can't take them into your bed, because once they get in there, they never leave." I nodded mutely, deciding that was the easier course than arguing how it all went against my parenting philosophy.
As my son got older, we moved him to his crib for the first part of any evening and brought him into our bed when he called for us. That became his only waking of the night. When we switched him to a toddler bed at age 2, he would walk to the baby gate at his door and ask to be picked up. Sometimes he's make it through the entire night in his own bed. Our move to Canada a few months later brought a short term regression; he slept in our bed exclusively for a few weeks. But then a funny thing happened--he actually refused to come to our bed. If he woke up in the middle of the night, one of us would go to comfort him, but he preferred staying in his room. All within 2 1/2 years, not the 5, 7, or more the detractors of co-sleeping all cited.
In our new place, he pretty much sleeps through every night. And when he wakes up in the morning, he pads into our room to tell me. Sometimes he wants to climb in bed with us, but really it's to cuddle and get us up. On the rare occasion he truly doesn't feel good, he will sleep with us, as he did one night last week. And you know what? We all slept better, my wife and I since we didn't feel the need to go check on him, my son since he had the extra comfort he needed right there.
*I know that a number of resources suggest that the baby sleep between mom and either a wall or rail with the bed snugged up tightly to it; this is due to the concern that mom's partner may not be as aware of the baby as mom. This arrangement, however, wouldn't work very well with our particular furniture and the space in our room. In addition, my wife was always aware of where our son was--I don't know if it's a gender thing or not.
**This was actually a breastfeeding issue. My son consistently refused a bottle during the day, and so he continued to nurse all night long.