The general rule of thumb is 1.5 x width of the window for a medium to heavy fabric; and 2x for a sheer or lightweight fabric.
The 2nd general rule is to hang all the curtains at the same level.
Although I love the floral fabric, I think the white would keep the room brighter.
I would first try to hang a panel at each side of the middle set of windows; and hang 1 panel on the left side of the right window, and the right side of the left window....so all panels are gathered at the 2 angled corners. this will give you access to the door; and also keep it balanced.

Do you need the treatment for privacy, or light control?
By the way...can you turn your furniture around so your sofa faces that beautiful view?

Thanks jeanjjk. You've been helpful!

We love the view but thought it would look funny to have the back of the sofa in the middle of the room?

Wrong. Place the sofa so that when you are seated you can enjoy the view you paid for! Place a lovely sofa table behind the sofa and put interesting decor on it of varying heights. Put two wing type chairs where the sofa sits now to create a conversation pit, with a coffee table in the middle.

Your space is all about the view and those lovely windows. Don't complicate it with the pattern. That will only detract attention from the view. Face the sofa towards the view with a sofa table behind if there is space. My first choice would be no coverings. The windows are spectacular as is the view. You might want to be sure there is a uv film on the windows if they are not north facing as this will protect your furniture and furnishings from damage.

However, if you want to soften the lines, treat the glazed area as one unit and place panels at the extreme right and extreme left. If there is no need for privacy then stop there. Full height would add drama. If you need privacy then add panels in between (where you have placed them - all same height) so you have enough fullness to cover when needed. Beautiful room!