I have basenjis, 5 now, the dog for people who like cats, and though they're allowed in the sewing room, it usually holds no fascination to them. From the time we were remodeling the room, we treated it like every other room in the house, meaning the door was left open, and they weren't chased out of there. Now that it's a sewing room, they don't care, because it's never been off limits.
I remember seeing on the web, a sewing room that they had actually built a lower cabinet area that had a dog crate! Darn if I can find it though, but when I googled, I came up with this site:
http://www.kevinandamanda.com/photos/den.html
They look nice,but my dogs would just chew them up, thinking mom got them a new toy!