Just my two cents. A planning document’s focus should be to communicate well with the client and project team, but especially the client. You’ve got to create planning documents that the client can understand, so they can look at the document and ‘get it’. Then they can approve it, because they get it, and you don’t get sucked into an iterative nightmare and infinite revisions.

A live wireframe is a fine idea, but if your client can’t understand it easily, there’s no point.