My sewing room is just over 10×12. It has a sofa bed so can double as a second guestroom if needed. It also has an ensuite. Very handy if I get caught short and also for cleaning my paint brushes. I redecorated it last year in a sea theme and recently swapped my old french wardrobe I was using for storage, for a larger model. My dummy gets conveniently tossed on the top when not in use. My desk is a good 6×3 and solid oak. I can cut out on it, or if I need more space, I use a cutting out board on the bed in the guest room.
If I have full skins of leather they get stored in there too. Just out of shot I have an enormous chrome ceiling fan. It gets hot here in the summer and table fans tend to blow the threads around on my machines.
This room is quite pared back, decor wise. My sewing room in our last house had an Egyptian theme. ( But then I was making belly dance costumes.)