We usually alternate readings from the Old and New Testaments, but this term we're going to do the life of David (and Saul, because he's in there too), three days a week; and Proverbs on Fridays. I have a list of chapters written out in our planning binder, but I don't have the exact verses picked out yet, just the names of the stories. The guideline for Charlotte Mason-style lessons in the elementary grades is about 20 verses at a time and that lessons should last 20 minutes (including narration); so a reading is usually just part of the chapter.
The list starts out:
1 Sam. 9: Saul chosen king
1 Sam. 10: King Saul
1 Sam. 11: Saul defeats the Ammonites, etc., through 2 Sam. 12 and then three extra lessons that I'm going to read out of a Bible story book, because of length and complicatedness.
I'm using ideas from the Rev. J. Paterson Smyth's guide Prophets and Kings, online here although a few lessons are missing. (I'm trying to order a used copy as well.) There's some excellent introductory material about how to teach Bible lessons; I think Charlotte Mason drew on his methods (she mentions his books more than once, and they were used in the PNEU programmes), although his lessons aren't set up exactly as the PNEU classes did them. I also like this Parent's Review article about Sunday School lessons--very helpful.