First let me start by providing you with our definitions of sleep! I've found people really vary on their idea of what sleeping through the night really means.
Definition of "sleeping through the night" (for an infant, up to 12 months): Sleeping/nursing for at least 5 hours at night without actually "waking up" and needing to be entertained.
Definition of "sleeping through the night" (for a toddler, 1-4 years): Sleeping for at least 8 hours without nursing or waking often.
1st: co-slept for 2 weeks until we decided to try the crib my dad had built for us (it is gorgeous). She slept through the night until 3 months old. Fought with her until she was 10 months old, finally came to our senses and she re-joined us in bed. Slept in our bed (or sidecar bed once she turned 2) until she was at least 4 1/2 (brother was 1 1/2 by then). Didn't sleep through the night again until she was 2 and night-weaned.
2nd: Co-slept from birth and slept in sidecar bed once he turned 2. Didn't sleep through the night until he was 2 and night-weaned. Moved in with his sister around 3 1/2 or so (when the youngest was an infant). Ended up back in our room (at the foot of the bed, on the floor) often until he was 4-5 years old. Was obviously not ready to move out.
3rd: Co-slept from birth and slept in sidecar bed once he turned 2. Didn't sleep through the night until he was 2 and night-weaned. Moved into a room by himself when he was around 3 1/2 (when the youngest was an infant). Slept pretty well by himself. Moved into a room with his older brother at 5 1/2 and now sleeps really well.
4th: Co-slept from birth and, by far, our best sleeper!! She started sleeping through the night around a year. Night-weaned herself. We're currently starting her on the sidecar bed at bedtime (can still nap in our bed) as the baby will shortly be on our bed and we don't want her "displaced". She can come in with us when she wakes in the middle of the night. She sleeps very, very well with us and has no interest in her bedroom across the hall which is currently not being used as a bedroom! As with all of our other kids, figure we'll try it again when she's 3 1/2 or 4 years old.
Never did use my dad's crib again. He's so sad. My brother just had his 1st baby and while it's in the nursery, I believe the baby's in bed with them. Oh, well!