My 16 month old & 4yr old nap in the same room just fine, but he's in a crib & she's in a twin bed on the opposite side of the room. She knows she gets in BIG trouble if she talks, plays, or gets out of bed for any reason other than going to the bathroom.
She generally goes down between 3&4, and sleeps for 2-3 hours, whereas he goes down whenever he starts rubbing his eyes & getting fussy. Tends to be somewhere between 1:30 & 4ish. He'll nap about 3 hours usually.
Sent from my old beater Android with no phone service because we're THAT broke.