for OT I had them read through chronologically, and know a list of facts about each book: who wrote it, when, where, how many chapters, what is it generally about, etc. and then had them read through each book and do a broad outline to get the feel for the book: what happened at the beginning, middle and end. after that, we used 2 bible survey encyclopedia ( one new white zondervan, one old dark blue can't remember the name and the book is packed right now) to get ideas about what 'scholars' had said, refined our outlines, hit points we had missed, and talked it all out. The kids ended up having read each book several times thoroughly, with a list of facts that I can use in oral drills and sword drills and a good working knowledge of location, flow and gist of each of the Historical books, plus a nice outline of each. and a million fun rabbit trails. (we have not yet done all the prophets).
NT is harder because the epistles are so packed, but we did a similar thing- know facts about the book and writer, read it a zillion times to get comfort with it, outline it, discuss specifics, discuss the gist. We found ourselves to disagree with some of the accepted interpretations of several of the epistles, philippians specifically- so often referred to as the book of "joy" we found to be much more about mixed groups getting along- loving your neighbor. 2Tim and passing the baton... what are the 3 things paul counted as accomplishments at the end of his life? etc
we also thought the christian liberty workbooks were pretty good for the younger set- chronological, with timelines,etc- though we didn't use them as workbooks per-se.
FWIW
-sarah