Well, if you already own the Westminsters Standards, you could go through those and discuss the Scripture references. My wife and I have done this with profit, and it helps you get to know your Reformed history too.
Some other helpful books for devotional purposes:
[i:c0732202ac]Morning and Evening[/i:c0732202ac] by Spurgeon
[i:c0732202ac]Hall's Contemplations upon the historical passages of the Old and New Testaments[/i:c0732202ac] by Joseph Hall (but this might be out of print)
[Edited on 3-29-2004 by puritansailor]