OK,
So I'mm guessing you will have one "clean room, and one not so clean.
In the clean room you will have have the corner samples. Let's say, on two walls.
On the third wall, some really nice framed samples you have done, and keep making more of, and rotating them. If you are a bit thin on them in the begining, bring in stuff from home, or use customers art that is ready to be picked up. Customers like to see more than mat corners, and frame corners.
On the 4th wall you will lean customers finished work. (It will stay cleaner in the clean room right?) (I'm guessing this will be the smaller wall with the dorrway and a window on it.)
There should also be one or two comfy chairs. A design table. I would build a 4 x 4 square base, and a 5 x 5 top. On the base, I would have shelving acess from opposing sides, giving you 2 foot deep shelves, that ware 48 wide. Mats on side, catalogs, on the other (as well a weights, work order forms, recip books/system and ledgers and whatnot. As well as tools for fitting.
It will be tempting to leave things on the counter top, but keep it free of junk. It is for customers art, and designing.
In reality, you will not have customers in this room all the time. Use this counter for final frame fitting. (it's the cleaner room, after all, less dust in theory).
If space permits, you can work in a way for customers art to be kept in this room too. (that clean thing again).
Now, this leaves the other room for the dirty work, and all the bluky stuff. Matboard and foam board, glass, and mldg storage.
Mat cutting, glass cutting, joining etc.
Hows that sound?