I will be leading a book study at church this fall, and I am 90+% certain I'm doing Galatians, one chapter at a time, then something from the next 3 books for the second half of the class. I do almost as well on the fly as I do with careful planning,* so leaving that open is not a problem, but an adventure. In my initial browsing, following a rather obscure trail I am unlikely to feature much in the class, I ran across this by NT Wright, which impressed me greatly.
I had liked Wright before, but I have noticed previously that you get really excited about an author when you are looking for an answer, and his is on the top shelf.
*Actually, that is unknown. I've never done careful planning.