Lots of electric outlets. I would love to have a continuous electric strip around the entire room at chair rail height so I could plug anything in, anywhere. There is never a place to plug in a fan in the summer or an extra sewing machine to do some ruffling or a coffee pot or a light box or an extra iron. I could go on and on.
The design wall is very important and I like to keep all my tools, (the few that I use, I am not a gadget collector) out in the open, not shoved in drawers so plenty of wall space to hang stuff and countertops. No cabinets, just selving. When everything has its' own station, things don't have to be moved around to make space.
The last thing I really must have is a wonderful spot for inspiration, like a bulletin board.
Have fun getting your room together and be sure to post as you go!
peace :D
Edit: I really like the idea of a sink. There is one close to my studio, which is next to my laundry room, so I didn't give it a thought! I am so lucky! to have all that I have
peace again! :D