I would go for the spare bedroom. My "guest room" is my sewing room. I have a twin bed in there and a sewing table that takes up where a second twin bed would be. Whenever one guest comes to stay, they get the sewing room and my bins of fabric stack underneath the table. Whenever two guests come to stay, they get my son's room with a queen size bed and he gets the twin bed. The room is light and airy with sun coming in the window. It's perfect to sew something for 5 minutes or longer.