Your room is beautiful. Your taste and ideas as shown in the room so far are great. Continue to use your own judgement as to the artwork. Artwork is personal...look for it on line, at art shows, art schools, maps, family photos, when you travel. My advice is always to be on the lookout for art that appeals to you. It will present itself.

Since you have given the size of the wall you are looking to place the artwork, maybe a professional can advise on size. Good luck

Given you have some rustic elements and some modern elements you might pick something that is not too modern. It is personal as mentioned above.

Here are some suggestions below for original paintings for your room. I have quite a selection of pieces, from bright colourful abstracts, to more subtle tones, abstracts, waves and florals. For more examples visit my website:
www.corinnenatel.co.uk and feel free to email me: design@corinnenatel.co.uk

Here's some suggestion for your wall you might like......to know more about my Art work and collections please visit my shop -

https://www.houzz.com/pro/poochoudhary/__public

https://www.etsy.com/shop/PooviArtGallery

*******CUSTOM SIZE AVAILABLE ********

Some simple floating shelves staggered or a single in Zinc or white with some simple decor on them that ties in to what you have in the room..... you can lean a black and white picture in a frame or a couple and put some candles or other simple treasures.