My space would be at least 25 ft square with pale yellow walls and would have:
1. Large windows on two walls, one with French doors opening onto a shaded patio where I can do handsewing and floor frame hand quilting when I wish.
2. A side wall with a 10 foot wide x 10 foot tall design wall and the rest in built-in storage cupboards just 14" deep to hold one stack deep of the way I fold fabric. Each section of shelves would be large enough to hold one color family...that's 15 feet of closed shelving! All batting would be stored up higher where I don't have to get into it often.
3. And at waist level there would be a large pullout section to hold fabrics as I audition them for projects.
4. Below those cupboards would be drawers designed to hold all my scraps, which are now in plastic shoeboxes and bins by size on shelves. Drawers would also hold things like hoops, weird/occasionally used notions, and the other collectible "stuff' we all seem to acquire.
5. Along the back wall would be a door into a powder room,
6. a washer/dryer and sink (for water to fill the iron, soak fabric, spot clean, dye, etc.
7. Next to this I would have a wall for hanging the tools I use not quite as frequently but for which I don't want to root thru drawers to find.
8. At the end of that back wall would be a closed cabinet for storing finished quilts and to-be-quilted tops.
9. In the middle of the floors would be two large 3.5 ft x 5.ft tables for cutting and pressing, both with drawers designed especially to hold rulers, cutting mats, rotary cutters, irons, water bottles for the irons, applique pressing cloths, etc., etc.
10. My sewing table itself would be "L" shaped, about 15 feet long, and be double sided with cut-outs for dropping in my machines. The "L" would accommodate a pressing surface so I wouldn't have to get up to press small pieces and would also support a large quilt as I finished quilting it. To my right would be a cutting surface for the same reason. There would be storage drawers at one end under the table so I could have my notions at hand and a thread cabinet. This table would also serve for basting quilts.
11. Lighting would be 'daylight' bulbs placed to eliminate shadowing over the sewing, cutting, and pressing tables and angled directly on the design wall and on the fabric shelves for use when I am auditioning fabrics for a project
12. The floor would be a non-carpeted surface with one area, perhaps along the back, that can be marked for laying out a quilt, measuring long lengths of fabric or batting, or hold chairs/tables for classes.
I designed this work space 15 years ago and, sadly, am no closer to ever having it than I was then! But we are blessed that we can dream, aren't we?
I guess I should add that if I could have this space, I'd happily live in a tiny house attached to it!
Jan in VA