Soft focus works well
I think that this piece actually looks better as the postcard sized piece, as the details get out of focus more, thus bringing the image into a greater perspective. I would suggest that you reduce the amount of white border that surrounds the piece, as I feel that you have just a little too much there.
I can certainly see why you've used the word "ethereal" to describe the piece. This piece really needs to have a nice slow ambient piece of music playing in the background, to complete the mood, but other than that, I might have pulled one of these points of light forward, just so that you could detail it a little more, allowing us to see exactly what you were focusing on there. After all it's all what you see from your imagination, isn't it?
With the colours that you've used, I think that the pastel qualities are shining through, despite them being quite dark, which is a relatively novel use for them. Perhaps use a smudging technique to flick the lights away, or give some halo effects to them, as it might enhance the image more.
[Review Request Club]