I have 4 bdrms upstairs all occupied by my teens and myself. I have a playpen in each bdrm which I keep set up all week except my daughter's room which I fold up everyday as her room has too much stuff in it already. Fridays I take down the other playpens. Fifth dcb I have in a main floor room on a soft mat.
There is a white noise machine or fan in all the rooms. I don't bother closing blinds; just too much work to do that 5 times....they get used to everything eventually. I find it's best to separate them if you can because not all fall asleep at same time, or wake at same time. My groups generally sleeps very well and if they don't they just babble until time is over. I have one that still cries occasionally but the others don't seem to care.
The only thing i'm not sure about is some of the kids are technically over the weight on the label of the playpen, but I haven't had any problems and they just lay there anyway. I like to keep them in as long as possible so they don't wander.