Upload & Sell: On
All valid points that you have mentioned. I like the silhouettes and color treatment.
Perhaps process one with the following:
1 - remove boat (I want to draw intersecting diagonals - bet they go through the boat) - a distraction
2 - if possible add more room at top - notice this gives three areas now rather than essentially two in the original
3 - remove horizontal line just below boat
4 - remove brush in center of image
I would not worry about the sole bird on right - the island helps balance that space versus the left.
<edit> Took the opportunity to play, hope you do not mind, if so I will remove the image. Not the cleanest job but you get the idea. And added a slight vignette to help contain the eye.