The views expressed here are my own, and not representing A.N.
1. I think this is a great pic. The only thing I would do different is to crop the bus out of the left hand side of the frame, as it is distracting, and maybe increase the overall pic size. (Perhaps start with your original 1500 pixel-wide pic, and just crop to get a 1024 pixel wide pic, without resizing at all if that's possible)
2. I don't like this one (sorry!) The horizon is a bit off (easily corrected), however, I think these types of pic need something SHARP in the frame to work (the 1st one works because the 747 is really crisp against the background). This pic doesn't work for me because not only is the aircraft blurred (understandable, with the shutter speed required for the shot), but the airport isn't sharp against the background either (looks like it was slightly hazy or misty). And it's too far away. To improve the impact of this pic I would: crop out the black part at the bottom of the frame, so the airport is right at the bottom of the pic; crop out everything to the left of the 737; crop out about half of the empty space to the right of the tower; crop out a third of the sky above the 737 (so the bright bit of sky leads the eye in from the corner of the frame); and finally try to sharpen a little more. I still don't think it would work unless you can get the tower or the theme building sharper on the horizon though. That's just what *I* would do however, and I'm not putting myself forward as an expert, merely offering an opinion.
3.I just don't think this shot works either. It's too dark, and all the bright areas (if you look at them) are ones we aren't interested in: the airfield sign, the lights and the reflected lights on the ramp. The airport buildings and aircraft, which are the parts of the picture we *are* interested in, are all dark, when they really need to be the parts of the pic that are well illuminated. Again, just my $0.02.
4. I like this shot. I do feel there's something not *quite* there with the quality but I can't quite put my finger on what. I feel like the 757 ought to be so sharp that it is jumping out of the frame at me, and it quite clearly isn't. I would suggest going back to the start, and redoing this pic again from scratch. Forget what you did to it the last time, and just see how much detail you can wring out from the original. Because it's not a bad picture - I just feel it could be better.
These are only *my* opinions (and what do *I* know?) Feel free to disagree with me if you wish. Just not too violently, ok?