like rich386 said the caging seperatly so they can see eachother works good, what i found works really good is still do the seperate cages but have the cages or the seperation really close to eachother, give them a chance to do a little pecking at eachother through the cage but yet they can...
Free ranging is great for your chickens, its also really enjoyable to watch them forage around, but having a run for them also is a bonus, it seems like letting your chickens free range gives them a nice brake from being fenced up and they seem to get less bored when they are penned up...