All of them are amazing art, that cannot be understated. Like bagel said though I think number 2 needs some text or something along those lines to make it feel like a lobby welcome image, it feels like its missing something. Similarly, 4 is a nice continuation of the original poster, it just feels a lil empty. I think it could easily be fixed if the floating station was larger on it to give more emphasis and fill things out. Regardless they're all much better than I could probably do, and look great :P
