I like the angle you shot this at, and as such, it makes an interesting entry. I would've preferred to see this reaching a little (ok, alot) further across the frame.
I don's see banding at all on my monitor, the sky is completely smooth. The position of the tower is, to me, quite right. Without the negative space to the right it would be too crowded. This way it has room to soar skyward like a rocket.
And I, personally, like your composition here. Think you could have gone either way, more in frame.. or as presented to us here.
The placement of the Needle is on an intersecting line, per Rule of Thirds. So.. works for me.
Caveats?
More of a suggestion.
I did take a look at the largest resolution size. And it is only apparent there, not at desktop resolution.. some ('some' being the operative word) noise is present.
I think you might have performed some noise removal?
If not, or.. if so.. here is another method (given how delineated and unencumbered the Space Needle is within frame):
Remove Noise (<--- to the point; a concise video tutorial for Photoshop ... perfect for your image here, methinks and if desired)
Last words (promise :oP)..
Been catching your images as of late and took a quick tour of your galleries, and I quite enjoy the fresh perspectives and uniqueness of your eye and camera.
Keep'em coming, keep shooting.. and happy shooting. :o)