My sister-in-law was a wonderful seamstress (not a quilter) and made her husband suits and all of her children's clothes and she did it all in her family room/kitchen. Then her DH made her a sewing room in the basement and she hated it. So, she moved her sewing machine back in the family room so that she could stir a pot once in awhile, etc. She kept most everything in the basement room though, out of the way. HTH
Oh yes, I know what you mean about the steep steps, my DD has a 2 story house and to get upstairs we go up a very nice, carpeted, STEEP staircase and it is horrible. I have to pull myself up by the railing. Absolutely could not carry anything upstairs too.