We are in the process of moving and my sewing room will be 18 x 16. By the time I get my longarm at one end and fabric storage cabinets there will be enough room for a large sewing table and a cutting table, but nothing more. It seems like a big room, but we quilters need lots of space for our expensive things. If you have the opportunity, I would make the room larger than you are planning, maybe 20 x 20. The loft idea is a good one. Remember to allot space for a comfortable chair for handwork, a TV and computer space, AND good lighting!