maybe wood blinds

I think a cornice board would look great here! It would add some color, but wouldn't take away from your beautiful view.

you could also do mock romans if you don't want to obscure the moldings.
this is inexpensive and easy :: http://www.beneathmyheart.net/2011/04/no-sew-faux-roman-shade-by-richella-at-imparting-grace/

Well, I just ordered unlined woven wood shades for my living and dining rooms.

I picked out one that was easy to see thru. I am having them start above the window to make my window look larger, but you can also have them fitted into the frame. Levelor has some without any valance, but their selection is sort of limited.

I think woven woods are sort of timeless and warm and casual. I am actually mixing them with some silk panels and I have some some sort of fancy chairs next to one window. Thinking it will be an interesting contrast!

HI -- I would keep it simple because that is a very nice window . Just some nice gauze like fabric (scrim) or a printed semi - sheer fabric hung high and wider than window on a chunky rod and rings . The tops can be soft fold (ripple fold) or gathered . Keep it soft and flowey . Romantic ! PS: Maybe paint the window inside cross framing black for some drama .