I would do two. Part of the beauty of those windows is that they are tall and narrow. Doing one would obscure that. You may be able to do inside mount. How do the windows operate? Does the top drop down or is it fixed? Do you open the windows?

Two

Perhaps hung above window, as inside mount may not work

Beings you have a lot of extra trim around the windows, I'm not sure Romans are the best choice. Where would you mount them? If you mount them on the flat part of the trim, just around the windows, they're going to jut into the room, meaning you're going to have a space between the shades and the windows. Not a particularly nice look. If you mount them on the wall, might look odd. If you made them wide enough to cover all the trim, would be too wide and if you made them narrow enough to just cover the windows, would look odd. I don't see a way to do inside mount, because the bottom part would stick out if lowered, unless you never plan on lowering them.

Have you considered just using curtains? Might be a better choice for your windows. Just something to think about.

It looks like you may have room for a simple, reverse roll, roller shade as an interior mount on the window. I'd look into that first. It would disappear when open. The moldings are really nice, and a roman shade would look heavy over that. If you can't make the roller shade work, I'd use drapes.