I would choose downstairs. You will probably be sewing well past the time you can navigate the stairs easily. I like to still feel close to my husband when I am sewing. When the kids all moved out, we converted one bedroom to his office and across the hall another bedroom became my sewing room. We really like this set-up. We are close yet still have our separate space. He's neat and I'm messy. We still have a guest bedroom for when the grandkids come over.