I like the vignette on #1 because there isn't anything else in the frame besides the plane, and it's feathered nicely, but as for the rest, I think it's too much. I think it hurts the other images. I do wish there was some motion blur in the props to add the feeling of a turning prop. Not sure what your shutter speeds were, and perhaps you couldn't slow them down at all without loosing sharpness in the rest of the image.
In #3 I really like the detail in both the boat and the shoreline, and I like the smoothness of the water. I think it works well. However, I find that with so much shoreline, and it having so much detail, my eye doesn't know what to focus on. To me, I feel like a vertical crop would put more emphasis on the boat, making it the focal point, allowing the eye to first fine the boat, then wander to the shore. I think it would give the feeling of being the captain looking for shore.
I rather like #4, the shallower DOF feels like it adds to the feeling of isolation. Like it was a lifeboat drifted ashore on a remote island. Again, however, I think the heavy vignette hurts the image.
#5 is a nice image, can't say I have any feedback.
#6 doesn't do much for me. Again, the heavy vignette hurts it. I'm not seeing much emotion in their faces. Kinda feels staged. On the bright side, it's nice and sharp, good exposure, nice background, and the conversion looks good.
Those are just my thought, and as always, I'm subject to being wrong!