I would consider matching the rest of the house.

I think you could do sills only in this style of house. I would not have them project far and I would do a separate one on each window.

@toddinmn I'm giggling, as the rest of the house is just a bathroom and laundry room. This is for a 900 ft guest house. 6 of the 9 windows will have sheer curtain panels on the sides (hiding the trim if it were there). The other 3 windows will have visible window sides. But yea, I am 'used to' window trim and sills too. But because i want to take the woven shades close to the ceiling, it forces me into outside mounts, which then hides the trim anyway.

I did a "no trim" look in my house with mudded in metal door jambs (so you have the strength of a metal corner and jamb without the look of a casing) and kerfed wooden jambs on the windows, so the jamb is wood but the face is drywall or plaster. There will be some paint cracking at the kerfed jamb on the windows, over time but it's like a hairline where it occurs. The door jambs are EZYJamb if you want to see pictures.

@palimpsest You used a few terms (kerfed, mudded in metal door jambs) I've never heard before...will need to do a little more research. Our drywall was finished today; they did drywall returns (level 4 finish). If we wanted to add trim at this stage it would be around the outside on the fronts of the windows. We did that in our current house and it still looks good 17 years later.