I agree with the others. We cannot help you design a space when we don't know what you are designing for. Sewing and quilting is so generic. Give us a list of the items you have and their size. Then list the items you want and their projected sizes. Do you already have a room? Are you building or adding on a space? What size can you go up to? Do you have a large stash, or very little fabric hanging around? Do you want a place to store a lot of batting for your longarm, or are you going to buy when you need to quilt something? I really like Warm & Natural and buy it every time JoAnn's has it on sale for 50% off.
As to myself, I have a wood dining table as my sewing machine table. It isn't the best answer, but at least I have a lot of space on both sides. I can look out a window if I want to. My iron is in this room. My longarm is sitting in this room, along with all my batting and all my quilting thread in roll around plastic carts under the longarm. I, also, have my quilting rulers, which I don't know how to use yet and other miscellaneous stuff in a couple of roll around plastic drawer assemblies. I have a separate room for all my fabric and kits, (this covers 3 of the walls on storage shelves) as well as 2 other sewing machines, a serger and a large, 6 ft, cutting table. It's one of those plastic ones that people use as buffet tables or overflow tables and I have the risers to bring it up to a good cutting height. It's in the center of the room so that I can walk around it. I bought one of those really large, about 60 inches long cutting mats to go on top of the table. It's great. I, also, have machine embroidery thread and size 50 piecing thread, all in labeled storage boxes with handles that I got from JoAnn's, on another storage rack in that room. Does it really work for me? It's a lot better than what I had, which was an 11 x 12 bedroom, but I really want to have an area that will have a couch so that my husband can spend time with me there, instead of wanting me in the house. Do I know what the best arrangement would be? Not really. It's still a work in progress.