If I'm in my sewing room, the cats are there...and lately our dog joins us. I think its a combination of them wanting to be in the center of our attention (companionable is a nicer way of thinking of it) and also a nesting instint. My cats love to find a "defined" space rather than being in the open. That may be whatever fabric I'm working on, fabric on the floor or laid out anywhere in my work space, etc. Outside of the sewing room, they choose a rug, a bag on the floor, whatever. But the sewing room is their favorite.