I would be inclined to put the 2 year old and the 3 year olds in the main nap space that the younger ones will eventually graduate to as well. Depending on the size of the 2 year old and if they have moved from a crib to bed at home they may also be ready for a mat or cot. I have my 1 year olds in playpens in family bedrooms and they move to a playpen in the main nap area around 2 and then size and weight also dictates when it is no longer good for them to be in the playpen. The one year olds may also be needing two naps or take one long nap from 11-2 or have fussy days due to teething etc so better to isolate them and keep the older ones together. It takes time but they do all learn to sleep in the same space. My rule about "quiet time" is that it is the chance for our body to rest and that means quiet mouths (no talking), quiet hands and legs (laying still), closed eyes. The more they relax the sooner they fall asleep. So even those that are old enough not to sleep have to lay down and do the relaxation period anyways and can get up when I decide it is time - totally depends on their morning behaviour and how much I think they need a nap.