Yes put it over the desk, it's lovely.

It's pretty but it does fade into the wall a bit. I agree with Sina that a frame will give it the visual weight that it needs.

If the canvas is a standard size you could go to someplace like Michael's and get a premade empty frame which is much less expensive than custom framing. They often have sales.

I like it a lot, but the wall will definitely need to be painted. Of course it won't blend in as much once the cardboard is removed.

Not much life in it but it is okay if you like the monochromatic look. I personally like to get original art that we both love instead of art that goes with my decor in fact I think we do our decor to go with our art to some defgree.

I mocked up white and black frames and much prefer the black. A wood-toned frame might also work well.

I Like it framed and centered above the desk. I know your not mentioning it but some curtains on that window that unite the softness of the picture may finish things off. I like the picture too !.

I would turn the desk so that it's perpendicular to the wall and mount the art centered on the side of the desk. Just a suggestion

Last one looks the best as the others take away from the painting. This way you absorb the art.