Depends what your design skills are like. I carefully trawled through dozens of curtain photos on Houzz, selecting the ones I liked. When I showed them to the curtain maker, she carefully explained how that not only did they not suit the rooms or my house (I have old-fashioned tastes in a modern house, was her way of putting it!) but in some cases they wouldn't even fit the windows. My advice is thus to get some advice from an expert first - you can always ignore it later, but it may save you some time. I'm now very happy with all the curtains suggested by the curtain lady - and I still have my dream curtains (pooled silk with swags, romans with fake swags . . .) in my Houzz album . . .

White curtains or very pale grey will keep the light levels high in your room and make a nice backdrop to your furnishings. I think patterned curtains are more casual and with the amount of windows you have, they would make a huge statement in the room. Darker curtains will reduce the light and can make the room look dingy. If you felt you don't want perfectly plain fabric, look for a slub fabric or something with some interest or texture in the weave. You could even have a self stripe which can look very elegant. I have just finished new curtains through my house and did the double track where I could and used a thermal lining that I can pull across to keep the cold out and it worked very well and is also working well now in the heat keeping the rooms cooler - in fact it is amazing some days the amount of heat trapped between the curtains and the windows and kept out of the room. In my bedroom I used a heavy sheer curtain to be able to enjoy the view of the garden while still maintaining privacy and the thermal lining gives me full privacy at night. I'm thinking this could be nice for your room when you have such a lovely outlook too and you do need something to keep the sun off your furniture and furnishings. There are also thermal roller blinds you could use instead of curtain linings, these do darken the room but they work very well. If you use the linings though, there are different weights, I used one pass in my bedroom and other rooms, and it does not darken the room very much at all. In my lounge room where I really needed heat blockout in summer, it was a bit of trial and error - I used triple pass and it does significantly darken the room to the point of totally gloomy - I really don't think I would use it again.

My advice would be to get rid of the blind as you won't use it once you have the curtains - perhaps you could use it elsewhere or have it as a spare. You would probably find that without the blind you will use the access more often. I would do full height and full width drapes - an inverted pleat is attractive with heavier fabrics but if you have the light fabric on the top keep it simple. How about putting your sheer lighter drape on the side closest to the bedroom and have the blackout lining behind. This gives softer look in your room. You would probably find that without the blind you will use the access more often. If there is a lot of sun take care with the pure linen cotton and natural fibres as they will rot with light and sun. There are many synthetic linen look alternatives that are less expensive, last longer and have the same look. I feel your room could do with some texture - you could possibly have a subtle self coloured stripe in the drape - or go plain and have the interest in your bedding. If you want to go soft grey drapes I would go for a darker charcocal or midnight blue/ teal colour on your walls which would look awesome with a soft grey linen look curtain and natural bedding. You could introduce soft mustard, peachy pinks and soft apple green linens in your bed cushions.

another idea if you had a plain pelmet that was within the alcove that came from the bottom of the picture rail to the top of the window and flush with the walls on both sides painted the same as the wall colour., you could then run your black curtain rod across the alcove pelmet which would look like the wall. When I had my Ferderation House we painted the bedroom walls up to and including the picture rail in the same colour. The wall above the picture rail and the ceiling were painted flat white, along with skirting boards, an old painter told me about this and it looks brilliant. A couple more photo's for you with different looks This is similar to what I have tried to explain by running a plain pelmet across the whole alcove and then the black rod running from either side outside the alcove with the curtains against the outer wall, the pelmet would look like part of the wall.