My son never slept in his crib. When he was about 10 months old we took it down and had him sleep on the mattress on the floor. Since he wanted us to lay by him at night, we ended up buying a twin mattress and putting it on the floor at 13 months. He got a twin captain's bed (very low to the ground) at about 17 months and we put up a bed rail to keep him from rolling out.
The only thing I wish we had done differently would be to have gotten a nicer bed rail that folded down; I ended up getting rid of it before he was really ready because he always wanted someone to lay by him and there wasn't enough room with that rail on the side.
A lot of the moms in our ECFE classes are struggling with switching their toddlers (ages 2-3) to big beds because they're so attached to their cribs. We never had that issue because he was too young to really know what was going on--or to care.
Best wishes!