I have two boys. With the older boy, I had both the bassinet and the crib, but within a couple of weeks he was in bed with us, where he stayed until nine months, at which point he couldn't settle while in bed with us (would wake up, see us, and want to play). Then he moved to the crib for both naps and nighttime sleeping.
My second son had a co-sleeper bassinet at first, but he was never actually in it, and usually slept on my chest. Then I discovered the wonders of a sidecarred crib.
I love love love it. I can reach over and pull him to me if he needs to nurse during the night, and then after a while when I wake up and see that he's done nursing and back asleep, I can scoot him back into his own space; then I'm free to pull up my big comforter, roll onto my tummy, and bury my face in my big fluffy down pillow, without having to worry about suffocating the little guy. If he wakes at all, he's still close enough for me to soothe (sometimes all he wants is to hold my hand, which just melts me). I find that I sleep better this way.
Also, there's now room for all of us--we were squished before, especially because my husband sleeps with his elbows sticking out at right angles from his body, and because our three-year-old joins us sometime in the early hours of the morning.
Now that I've discovered this wonderful arrangement, I'm getting rid of the bassinet. I am going to buy a pack-and-play, though, partly to use when we're traveling, but mostly because I'll soon be caring for a friend's infant, and will need a place for her to sleep.