After digging into markdown, multimarkdown, and pandoc today I've decided I was way too hasty to assume that I couldn't use it. Markdown for simple fiction is dead easy to use. I was able to use pandoc to turn my existing text file into pretty good looking xhtml, pdf, and EPUB with no alterations whatsoever to the file. Clearly, this is a lot closer to writing the way that I want than any other markup language that I've used in the past!
to everyone who suggested that I look into this!