I can totally understand why you cannot change the blinds. Can you perhaps get matching ones for the great room lower windows to block the west sun? I know that Hunter Douglas makes remote control ones that run off one control. You could use them interior mounted for the higher windows. A coworker got them for her top windows in her foyer that face the west and she loves them. If you got matching ones on the family room bottom windows to your kitchen shades that would give some continuity to those adjoining spaces and you wouldn't need the drapes to have to close. That would save you a lot of money in material. With all the online retailers, I would think it is possible to find drapes. However, it may be pricey even if they are stock. But, I really think that would give a majestic look to your room.

If this is a first floor room you might need to cover the entire window? If so, I would consider plantation shutters. If it is a second story room you could just go with cafe shutters or cafe curtains. I much prefer natural light rather than using shades.

The more shades the more options you have for light/privacy control. I would recommend 4. Woven woods do create a lot of stack when up. So you lose much of your window. EcoSmart Cellular Shades, are energy efficient, low profile(when not in use, you BARELY see them) Below are shades paired with drapery, which can soften the look. The drapery can be stationary panels instead of full operational drapery, which could be difficult with your sofa.

Very pretty room--I love the French vibe. Yes, there are designers and companies who sometimes only do window treatments as a specialty. I am sure that you can find a company in your area to do them for you. They may be able to do an "inside mount" if there is room, so that there would be no drilling holes in your wall or ceiling as you mentioned. They will be able to help you with the style, fabric, hardware, etc. Good luck--it will be gorgeous.