We like to get our kits out of the nesting box to play and hop around. It is cute to see them explore and sniff and climb things. But we also have to be careful to make sure they don't go behind big pieces of furniture and get lost. It is fun to try to keep track of all of them, since there are six of them going all different directions. And we have to make sure we do not scare them or squish them when we are picking them up.
We take the nesting box out of the doe's cage and let the kits hop around. That way we will have all of them out at the same time so that we don't risk having any kits miss a feeding. We always put our kits on the carpet because their muscles are still developing and if we put them on wood or tile they could develop splay leg.
We take them out so they won't be skittish and will be used to people. They also like to be handled daily and they need exercise. Of course, they get exercise in their cage, too, but if you let them run around in the house, they can get used to your other pets. It is also important to have all of the kits out at once because it lets you observe them as a group to compare and see if anyone is lethargic or looking sick.