This sub-project has been a great learning exercise for me. I've gained a greater familiarity with C# and windows forms in .Net, but I've also learned more about productivity and when being less elegant is okay.
As I've stated previously, I spent way too much time completing this tool (although, as a learning exercise and considering my busy-ness, it's not that bad). I've learnt that there's two things that need to be of good quality with a tool (especially a tool that will most likely only be used by yourself and possibly a select few others):
1) The user interface should be easy to use and efficient to work with. The primary focus of a tool should be to alleviate the tedium of hard-coding data or assets yourself.
2) The output of the tool should be reliable.
Basically it doesn't matter if your code is horrible spagetti-code (unless you're planning on coming back and working on it later and have to understand what you've written) because the final product (your game) will not touch it. It doesn't matter if there are bugs in your code, as long as they don't affect the usability or the quality of the data output (although I don't think I've got any bugs, fingers crossed! [grin]).
This may seem obvious to others, but it's been a bit of an exercise for me to not put in every feature I could possibly want or re-write for the most optimized and elegant design. I had to just get it done so I could move on.