PhotoNewt, that was very helpful. I appreciate you taking the time to point out the things I can improve on my photo and offering other suggestions.
I think the problems came down to post-processing as I used a tripod and took multiple exposures. I will look seriously into a GND as blending exposures gets to be a real tedious task sometimes, especially when there's a lot of detail in the horizon line. I've found that using a soft air brush and switching between slight gray and white on the layer mask helps a lot to smooth out the blending, preventing haloing.
Here's an improved (hopefully) version of this photo:
I've played around with HDR. The tools I have available on Linux are somewhat limiting, so I haven't had the greatest results. I do have some that I like, such as these:
http://www.flickr.com/photos/dorkyph...er/2666945535/
http://www.flickr.com/photos/dorkyph...er/2662072449/
http://www.flickr.com/photos/dorkyph...er/2662787182/
http://www.flickr.com/photos/dorkyph...er/2644172535/