My four month old has recently gone from her bassinet to a single bed size futon on the floor. She co-sleeps with us for the second half of the night, but sleeps on her futon for her day sleeps and the first half of the night.

The futon is next to the wall and has a mat next to it in case she rolls off. So far, no rolling off though. I don't really see the point of a cot myself; when she goes into her own room we'll make sure her room is safe and put a baby gate on her door.