We replaced it with a twin mattress on the floor.
I'm not usually the type who's all, "My baby's growing up" *sniff sniff* but I was getting sad as we took apart the crib. He really is growing up. Look at that picture up there. He almost fills up the entire crib mattress.
It seems like these transitions are often much harder on me than on Ben because his first night in the big boy bed was perfect. It was like any other night. And it's been that way ever since. Naps, bedtimes, it's like nothing has changed. Plus, we have the added bonus that sometimes when he wakes up he'll play for a little while before calling to us. Extra sleep, FTW!
So much of parenting can be a fight or a hassle, it's wonderful when something is just easy.