I use DevonNote for just this purpose. It opens quickly and is the place to save notes, files, URLs, and other matter related either to courses or possible essays, reviews, or books in progress. I’ve used it to plan lectures, organize classes, and line up evidence for chapters. After I while, I export the folders to the Finder or import them into DT Pro.
Personally, I would prefer to use DT Pro for writing projects and DT Pro Office only for importing e-mail or scanning and OCR of paper documents. But Annard tells me it’s not good to have them both in the Applications folder, since that may confuse AppleScripts and Automator about which app to contact.