I'm with ryan (at least at the conceptual level): you really want to NOT use WP 'Pages' to implement this. Your easiest solution is to use categories themselves (writing as parent, haiku and exercises as children) for organization, then as needed make custom category templates where you want control over the category 'views' of posts.
Okay, question. I am using categories for organization. Haiku is cat=11, exercises will be cat=14, etc. I have now created a Page Template that queries cat=11, then formats the page. I have ALSO created a Category Template for cat=11 and formatted the page. I get the same results.
The difference I see is that using the Page Template method, I'll get the page (in this case a child page) listed in the wp_list_pages. Using the Category Template method, they won't show up there, and will instead need to be manually placed in some nav list (across the top or along the side) manually.
So, my question, are there Pros/Cons to one way over another? Seems the Page Template will work just fine, but a few above have said don't go there.