I think the second photo is better than the first. The first photo's composition is a bit off to me. The subject takes up so little in the frame, she almost seems to be a distraction or an after thought in comparison to the rest of the photo.
I think Striker's crop is probably the best one I've seen here and what I would do if I were to make any adjustments. The color enhancement is good, too.
In the second photo, I think you could probably crop the left side and top away. One thing a lot of people do when they start taking portraits is leave a ton of room at the top of the photo. To me, all that area above her head is distracting, as well as the red junk under the pier to her left. You don't want your eye to wander that much, especially when it doesn't come back to the subject. You don't always have to crop the top out of the photo, but I think it would help in this case.
David Ziser has a lot of cool composition tips in his blog Digital Pro Talk as well as his book, Captured by the Light. He's mainly a wedding photographer, but a lot of what he discusses in his blog and book are applicable to any portrait type photography.
If you're looking for software, I would recommend Photoshop or Lightroom. Personally, I prefer Photoshop because it has more options just in case you need them. You get a lot wider range of actions options if you ever go that way, too.
I'd also recommend checking out books or videos on Adobe Camera RAW. I never realized how powerful that software is until I watched Scott Kelby's video series on it on his online training.
You could also check out Totally Rad Actions. I have the first batch and plan to buy the second at some point. I'm also a huge fan of Alien Skin's Exposure 3 program.