Your room is going to be beautiful. You really can do a lot with all the space. Make sure you have a good cutting table. I'm sold on my adjustable supports from IKEA. They look like saw horses but are wonderful. They can be adjusted lower for a sewing table when needed and adjusted higher when cutting. Really saves on the back. But then again I don't have as big of an area as you do!
I can see beautiful wooden shelving for sewing supplies and a beautiful closet when you walk into it you see a beautiful display of nicely folded fabric. Lots of lighting throughout, may be you can have the outlets put on the floor so your cords aren't standing out. I could go crazy with this room I'm so excited for you. Please send pictures with the progress.