Coming back to this, it seems to me that the main failing of the image is the background detail. The asteroids lack detail and features to make them interesting, as well as depth. The hangar itself really suffers because I didn't have time to texture it properly.

What I think your scene needs is a little dirtynuts shader for the asteroids as-well as the hangar door, Space is a very dirty place and years of accumulated dust and rust would show on the outside hull. My second issue is how the two flying ships look to uniform and just duplicated. I suggest making one the flying ships angled differently , right now they just look like clones. The stars, its all about them stars.Try this. Open a new scene and put a default object sky into your scene. Now make a material and in luminance and color channel ONLY put a Starfeild shader on. In luminance set the brightness to 5000 by typing it in the % box. Do the same with the color channel. Now put the material on the sky in your scene and then in the material tag properties set the Tile X and Tile Y to "2". Now press render, what a beautiful night sky :D

Actually I disagree about the hangar needing dirt. I don't think that there's any way that in the future, the accumulation of amounts of dirt that were visible would be allowed in a hangar area. Just take NASA as an example - most of their work is done in sterile conditions. There is a starfield shader there, but it's not boosted. It got a little lost under the interlacing effect. (you know, you could just have said 'starfield background, luminance and colour, 5000%, 2x tile'... I'm not a simpleton.) The two ships differ slightly in their angles, but I found that a larger difference made it seem as if either they werent flying in formation, or were about to collide.