I have my sewing studio in our basement. It is the biggest of the four bedrooms in the house. I had to wait for the last kid to move out and I was in there! Course another one came back from college to finish school here....didn't give up my studio though....we stuck her in the other downstairs bedroom. Now another kid is home so we can help them to understand how to raise a kid....wow.....put them in the other room since the college kid moved back out. I have managed to keep the studio as mine. We just stick the kids in the guest room. I am using my rec room as the temporary guest room.
My studio is 11x18 and houses all my fabric, all of my sewing machines except the antique ones, my quilt frame, and all my extras; supplies and such. I also have an upstairs sewing area with a large sewing desk. It sits right in front of a large window that faces a field of cows....talk about relaxing!
I do most of my sewing upstairs as I like to be around the doors and such for when the dogs bark, someone knocks.....I do my quilting downstairs. I also have my "creative moments" (matching fabrics...TV watching) in my sewing studio.