Nice picture Eskilady. You know, the only other thing I don't like in all these pictures are all the jet vapor trails. I guess we're stuck with them unless it gets overcast. I do like the blue sky shots, though.

It seems to me that your horizon is pretty straight. I believe that lenses are subject to different types of distortion based on their focal length (such as pincushion distortion). When taking pictures with a tall subject near the border of the frame the top and bottom will tend to lean toward the center. Exactly why this happens I will leave to someone brighter than myself. I believe the only way to really correct for it is to use a shifting lens to alter your focal plane.