There is a terrific book by Lois Hallock "Creating Your Perfect Quilting Space" that might be helpful. Of course looking at all the wonderful examples here on the board would be helpful, too. My room is 12x14 and I would love it to be at least twice as big.
Lots of natural light. PLENTY of wall space (you can never have too much design wall space!). As many electrical outlets as you can get and do not let them put them down at the baseboards - who wants to be crawling around on the floor all the time to plug stuff in. If you have a modern sewing machine (lots of computer boards) be sure to have a dedicated circuit for that so you don't run the risk of blowing a fuse or having a brown out on your machine.
Other things --- ceiling fans for summer --- radiant heat for those cold winter floors.
Yummm! Have fun and enjoy.
