I recently gave my cot away, before we realised that #3 was on its way. i also have to decide whether to get another one. i have a hammock that both kids have slept in, alternating with bed sharing. Neither kid has been happy in the cot, as a cot. We had the cot as a side car for awhile, and DD slept in it a bit between 15 and 18 months. She moved to a king single bed at 18 months. DS moved to a single bed (part time) at 12 months, and is still transitioning.

Having a cot for baby to sleep in would be handy because you know even if they wake, they are usually safe in there. I had to be ready for when they woke if they were sleeping on the big bed, or even in the side car cot once they could crawl. they were able to get off the big bed from a young age, but there is that adjustment period when their enthusiasm is greater than their skill level. Feeding them to sleep on a mattress on the floor was another option i used, but similarly they could still get off when they woke (just more easily and safely) so i had to listen for them waking or know the house was safe if they went wandering.