I'm finding this very interesting. Hubby and I are in the process of having a house built. My sewing will be a room that is 10' x 15', and it will have to be a guest room when needed. The good news it that I made sure it got a walk-in closet that is 7' x 7' (the closet also has an access door to additional storage under the staircase). My Bernina is in a cabinet but I need to plan what furniture pieces I will be adding. I currently use the dining room table as a cutting table so I definately need one, but also sewing space for my serger and a second machine.
Hubby is a woodworker, so eventually he will build me new furniture for this room. (Have to build the shop yet so this is a ways down the line) We have planned a murphy bed that will have a drop-down table that can be used when the bed is closed. I thinks this would be a great way to use a sewing room as an occasional guest room. This is a pic of one I have seen online that I told him I want one like:
[ATTACH=CONFIG]400349[/ATTACH]