Keeper of the Plains and city night shots, C&C needed

[silvrbullet]

I have owned my 50D for less than a week, and am very new to photography. All comments, tips, tricks etc are welcomed!

All Images were shot in RAW, on manual mode, on a tripod, and processed through Lightroom. When I exported them to JPG, the sky on a few got a little pixelated- I'm not sure why. The only processing done was WB and noise reduction.

1)
http://i21.photobucket.com/albums/b272/silvrbullet/Canon50D/TheKeeperofthePlains2.jpg

F/6.3 @ 30 seconds, ISO 100

2)
http://i21.photobucket.com/albums/b272/silvrbullet/Canon50D/TheKeeperofthePlains4.jpg

F/16 @ 30 seconds, ISO 100

3)
http://i21.photobucket.com/albums/b272/silvrbullet/Canon50D/buildings.jpg

F/11 @ 30 Seconds, ISO 100

4)
http://i21.photobucket.com/albums/b272/silvrbullet/Canon50D/Wichita1.jpg

F/9 @ 30 Seconds, ISO 100
In Lightroom, the sky looks completely smooth, and not pixelated. When I exported it as a JPG, it looks less than desirable.

5)
http://i21.photobucket.com/albums/b272/silvrbullet/Canon50D/Bridge1.jpg

F/9 @ 13 Seconds, ISO 200

6)
http://i21.photobucket.com/albums/b272/silvrbullet/Canon50D/Bridge.jpg

F/10 @ 4 Seconds, ISO 200

7)
http://i21.photobucket.com/albums/b272/silvrbullet/Canon50D/TheKeeperofthePlains5.jpg

F/11 @ 4 Seconds, ISO 100


Thanks for looking !