You could hang the treatment flat against the outside of the bay like it was over a flat window. My parents house has the sheers against the bay on a bent rod, ceiling mounted (probably with molly bolts) and a heavier drape mounted on the wall in front of the bay on a conventional straight rod.

I'd do inside mount roman shades--with a thermal lining. If you want to "dress it up" a bit more you could add stationary panels to either side hung closer to the ceiling in order to draw the eye up. I would not have them operable because would look odd paired with the floor bump out.

I would do woven wood blinds with a blackout lining, something that picks up the wood tones in the floor. I think the narrow walls on either side of the bay, plus the fact that it is not very deep, make curtains feel overwhelming, and too much for the nature of the room as a craft/sewing room.

I can't tell for sure, but it doesn't appear that there is casing around the outside of the bay, just the sill and apron. I would add casing that matches what is around your door, for a more finished and defined look.

Thanks so much!

Valinsv, I had thought about doing Roman shades, and I think that would look great, but...I'm afraid the hardware/mounting wouldn't stand up to the raising and lowering of the shades.

I think my fastest/cheapest/most sturdy bet is to hang them flat, like Palimpsest suggested.

Les, I would love to add casings, but that would be low, low, low down on the list. After the fence, gutters, other misc. repairs, etc.

These particular windows weren't installed properly. They don't open and close like they should, and they're drafty. We're going to caulk around them as best we can until we get to the point where we can replace them. If I had my way, we'd replace the whole bay altogether and turn it into a traditiona, flat window, but I imagine that's cost prohibitive. That room originally was the garage, so I have no idea what, if any insulation is in the walls. Adding insulation is also on the to-do list.