Amy,
I think you made the correct choice when you began with a Page Layout document, but Page Layout mode requires some study to learn how to best use it. The only case that can be made for WP mode is if you need to have a Table of Contents or Bookmarks or if the size of the document is in flux. Since PL docs are typically small and of fixed length, typically newsletter or poster/flyer, there is no advantage to WP except for comfort level if you haven't learned to use PL.
It takes more skill and understanding to properly use PL-like features in a WP template, because you have to be on guard for issues that crop up on a WP doc that is loaded with graphics and text boxes.
Edit: You may find that you prefer to compose in both modes, separate documents, and combine them in PDF form within Preview.app. That way you can also combine Landscape and Portrait pages into a single file.
Jerry